BAC Forum
General Boards => Technical Support => Topic started by: Adam Hicklin on June 02, 2015, 05:38:21 AM
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Someone asked this as an aside in another thread and I realized I had the same problem. On a cold start, when I turn the key to strart the engine, it sounds like the starter engages and maybe gets 1 revolution in, then there is a hesitation. Maybe a second, then it turns over and starts. If it has been brought up to temperature, it starts without hesitation. When it hesitates there is always a part of me that wonders if it's going to continue to turn over. I know at least one other person has this problem because they brought it up in another thread. Any ideas? Batteries are charged and I wait about 15-20 seconds with the key on before I attempt to turn it over.
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There are a few areas of problem. Even battery's are charged and test good sounds like a loose
connection. ( the starter needs to spin 150 rpm's to start engine ). Second connection on the
starter itself loose or dirty. Starter solenoid inside a disk about size of a silver dollar contacts pitted
and not getting a good connection. Starting after running with no problem also sounds like one battery
weak and has a surface charge, running engine put a charge into battery.
Dave Atherton Retired Cat Mechanic
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I had the same issue with our 06 PT, I could just hit the boost and then had no problem. While in AZ waiting for parts Tom At Massey suggested that we add a 3rd chassis battery and this has done the job, I think the C13 need more amps.
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Adam,
In addition to what Dave has brought up you could have a weak starter that has been damaged but I would not start there. Check to see if your starting batteries are being charged with 13V or more when sitting. Clean the battery posts, both negative and positive as well as the parallel jumper connection points. There is a round wire brush tool made for this and spray your connections once cleaned with CRC Battery Connection Red Spray. If any corrosion is evident use Baking Soda and water to neutralize it before cleaning things up. Check the large lug and wire on the starter solenoid to see if it is tight and clean. That is hot all the time unless disconnected at the battery.
You can try your emergency battery switch as a clue as to what might be happening. Hold it down for 30 seconds and then crank while holding it down while everything is cold and see if it cranks normally. If it does that will tell you that if you had more current available, your system would crank and start normally. I would do the cable cleaning first, if that did not work, then the parallel jumper test, if that worked I would probably get a new set of quality batteries especially if yours were more than two years old and see if that worked.
If you know the charging system, batteries, cables and connections are good then the starter and starter solenoid are next to get checked out. Hope this helps.
Later Ed
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Adam,
I'll raise my hand and plead guilty as the previous poster on this topic. We have similar vintage coaches, yours being just a year older than mine.
I've simply assumed that it was a partially discharged chassis battery because like yours I believe, my coach has the rear engine fan that runs about 30 minutes after stopping. In addition I leave my coach stored for weeks at a time now, with the chassis battery disconnect (this discussion is well documented).
One thing I do is, and its according to the manual, is to turn the key on, and this is supposed to allow the diesel heater to operate, then after about 15 seconds, I turn it off and repeat, then start it. Sometimes that works and sometimes I get still get the issue.
I'd read a post regarding the fact that the solenoid in the Electrical Basement Bin might be a problem because I believe a poster said that he couldn't get the starter to even begin to operate. I think Gerald posted something about a $20 continuous duty solenoid as being the problem and I promptly purchased one feeling that mine was failing. I thought the post was referring to the one in the electrical basement bin, but then the actual starter solenoid was discussed. Any way now that 2 of us are basically asking the same question, perhaps someone knows if this might be an indicator as to whether or not that solenoid in the electrical basement bin might be failing OR it could just be that I purchased that part on amazon BUT totally misunderstood what for.
If its not that part, then in my case, knowing that my chassis batteries are partially discharged while stored (2 others even say they are "dead" at 11.7V), that may be my problem and yours.
What does your computer show for chassis battery level before you start the coach under these conditions? I would suspect it might show 12V or under as mine typically does.
Also, in this situation, had your coach been sitting for a day or overnight WITHOUT having disconnected the chassis battery? It is well known that the ECM does draw charge in this situation, so that might have led to the voltage drop, in ADDITION TO the rear fan running long after the engine has stopped.
Glad we're talking about this again as I've never resolved what that part was for that I purchased from amazon.
Thanks,
Mike
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Adam,
Like Ed stated, check for corroded cables, and then try to hold down your boost switch when starting the coach. If that corrects the problem, there is a very high chance that your cranking batteries are the problem. Have them checked with a battery tester that reads CCA (cold cranking amps). A least one of them will probably read in the 700 CCA range, and that is too low to readily turn over a C 12, especially if it is cold. If you replace one or more of your cranking batteries, buy one with at least a 1000 CCA rating or more. Cranking a cold C 12 takes a lot of amps.
Gerald
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Mike,
The $20 solenoid in the side front electrical bay is to power up the right buss when you turn the ignition key on. The contacts in that degrade with time and it can lose contact while driving and shut the coach down just like turning the key off. Some have had that issue and have changed it and some change it to prevent that issue from happening. I would call this an ignition switch solenoid and not a starter solenoid so as not to be confused as to which one we are referring to.
The starter solenoid is large and is actually on the starter on the C12. Your C12 does not have any heating that takes place with the key switch (like a glow plug system would) so there is no need to hesitate with the key. If it is cold, say below 45 degrees, there is usually some engine heating system on the coach. Mine uses a circulator from the Aquahot and a copper coil to exchange heat and heat the engine antifreeze. It probably takes a half hour to warm the block some. Should be some info in your manual on how to preheat your particular engine and coach configuration.
Later Ed
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Ed,
I do understand that manuals can be outdated, or otherwise not representative of the coach sometimes. The manual, and I guess I'll have to find it, states the same thing for both the generator (except that it does the preheat automatically before its starts the generator - about 5 second delay) and the C12, and that is that a small diesel heater does preheat the diesel, so they state that you do basically as I have done. I too have a preheat function for preheating the coolant in my C12 by way of my oasis combi.
Like I said, the manual may not match what is actually going on, but then too, my gut feeling is that things could also have changed between our model coach systems. I'll try to find the manual but I believe it was in the Beaver Owner's manual (not the caterpillar manual).
Thanks for the info on the ignition solenoid. I have one if I need one now, but am less likely to replace it now given that it would not resolve the issue about the starting.
As a further note to Adam, my chassis batteries are 1 year old, so I think its possible yours are fine. Just appears that they are slightly low, so like mine, they do start the coach, just not as nicely as you have that delay, the alternator then takes over, and if you stop along the road, then restart there's no problem. I hope that's the case, rather than having to purchase new batteries, which in my case didn't solve the problem - though one did test bad and that's why I replaced it, not because of this issue.
Thanks all,
Mike
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Mike,
The head of the C12 is a complicated affair with an extra valve train for the Jake brake. It is also a large displacement and Caterpillar chose not to try and incorporate any glow plug system (not sure it was even possible). That means that when you turn on the ignition, you could wait all day and there is no heating function. The Cat diesel has high enough compression and cranking speed that it will ignite fuel well with just cranking but that is limited by temperature. I preheat at about 45 and below. When they mention it has a diesel preheat that is the Oasis system diesel burner heating the engine coolant if it is like mine. That will take close to a half hour or longer depending on the block coolant temperature. The generator has glow plugs and that works in 10 seconds or so to heat a spot in the head to start ignition of the fuel.
Later Ed
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Ed,
So you're sure that my coach doesn't have an inline fuel heater located between the tank and the fuel filters?
You're absolutely sure about that?
Thanks,
Mike
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Mike,
There is a place in the bottom metal bowl of the Racor filter housing to add a fuel heater but I do not think we have that function and if we did, it would not do much. I think the way our fuel systems work is that the extra fuel that is pumped passes through the hydraulic driven injection system cools it and then cools the ECU and is then returned to the tank, so it is a loop. I think whatever fuel in the bowl that would have been preheated is mostly sent back to the tank. This may not be exactly right but I know of no specific preheater in the fuel line. While you drive if your system monitors fuel temp like mine does, I have seen it climb to 130 degrees while it is doing its cooling. There is a limit on fuel temp, I think in the range of 170F, and that is part of the monitored parameters by the Cat ECU.
The C12 fuel ignition relies on cranking speed and high compression to do the fuel ignition. At some point due to low temperature most all C12s rely on a water jacket block immersion heater, an oil pan heater on some, or an external antifreeze circuit loop like we have with an external fuel burner.
That is my understanding, if you are in doubt, then Gerald is another source, or you can take your coach into a Cat dealer and pay them to look yours over and explain how your preheat system works. You seem reluctant to believe anything you see as an answer on the forum and that is frustrating. For the most part if folks post an answer, it may not be a complete answer, but it is usually a pretty knowledgeable source from some experience.
Later Ed
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Ed,
See, now we're on the same page. I spoke of a fuel heater and you were talking about the engine heater. So now we're on the same page.
I am not reluctant to accept answers that make sense to me. I may be a little different than most people for that reason, but, frankly, accepting answers that don't make sense, is what's creating such an issue in this country. So, I'll continue to look at all reasoning on this forum and anywhere else reasoning is used to see if it makes any sense to me. I don't need to be categorized in any particular fashion by anyone.
So, I'll ask for help from anyone who's had the same practical experience, like allowing their coach to be stored without power for 6 weeks, and can tell me their experience doing the same thing. And that will help. Guesses about things can sometimes lead to being more worse off than if the answer wasn't given in the first place.
In this particular case, my question and Adam's were identical and my actual experience is relevant to the issue at hand. I am not guessing about anything, and have merely related my experience and what I've done on my end towards working the solution.
That's what we're supposed to do here - I think - like "Oh yes, I had that exact same thing happen, and here's how I fixed it."
So, what I try to do is look for things that I've personally seen, and then help out. And when I have a very specific problem, then I ask for help, hoping someone's "been there, done that".
If I am not doing this correctly, and I should get out my volt meter and slide around under my coach more, then maybe others will chime in and let me know. :)
Thanks,
Mike
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Mike,
Your first post was about a "diesel heater" that ran off the ignition being paused. That is what is typically done for a glow plug system, which is why I went there. Your follow up was about an "inline fuel heater" which we also do not have and if we did, they are used to keep the fuel waxes from gelling in the filter, so the fuel will still flow at very low temperatures. If we had one of those type heaters, it would not help with engine preheating.
I guess we are on the same page if you now believe that the only preheat you have comes from the separate diesel burner in your Oasis system, and that is only activated when you allow the engine coolant to circulate to it. Also, that turning the key on and waiting has no real purpose here.
The thing that I am not sure about is how long each of these varying external heater and circulator configurations take to heat the block at various temperatures. For my Aquahot, a half hour has not been too long at below freezing temps (low 30s/high 20s). The block feels just slightly warm to the touch at that point...it is a big thermal mass. Given it is summer, we should not have to worry about this subject for awhile anyway.
Later Ed
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Sorry, to me it made sense but my wife is always telling me I don't say the right things. "Diesel" as in the fuel, and heater as in heating the diesel fuel, so I knew what I meant. lol
My user's guide for the combi says about 20 minutes, and though I don't think I've used in in temps below 30, that figure was correct, at least according to my Silverleaf which showed significant rise. Of course I have no idea where the silverleaf sensor is. But I've just let it go until I see 100 or so, then I start it up. The old hurricane manual I thought seemed to suggest hours like 4 hours or so, but I'm not sure.
I do have a question on that though. Since the combi heats my combi coolant to 180 or so and keeps it there, would it hurt the engine which mine is set at 188 if I inadvertently left the pump on after starting up? Books say don't do it - I think I've done this one time in the past.
Also, if I want to heat the interior space WITHOUT THE COMBI BURNER coming on, and assuming I am up to temperature in both the combi and the C12, would the combi to engine pump (engine preheat button on) being turned on help at all with moving heat to the combi from the engine or is the "water pump" in the C12 going to do much more than that pump anyway in getting water to the combi?
This if getting off the original topic, but we're here so be it.
Thanks,
Mike
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Mike,
On my Aquahot I found that the C12 would heat mine without the circulator preheat being on. You can feel the hoses and see if you have run the C12 for awhile if those hoses that are on the preheat circulator are hot. If so you should be able to run the zone heaters with the burner off. I do not see 180 vs 188 being any issue.
Later Ed
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Thanks for the discussion. I really didn't think it was a problem until I saw Mike's question in another post. I asked it hoping someone would chime in and say it's just an idiosyncrasy of the C12 (I never get that lucky!) but to answer some questions, my coach is always plugged in while sitting. I'll pay more attention to the battery condition before starting and have the chassis batteries tested. I'm sure a cleaning is order at the very least.
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Adam,
Thanks, that might also tell me that my issue is simple cleaning as well - though I thought perhaps it might be the solenoid in the electrical bay going bad.
The battery compartment is fine, but I've never even looked for the starter. If I face my coach from the rear looking in on the engine, no doubt the starter is beneath the engine but is it to the left or right?
I guess when I go to pacific shores next week, I'll roll under and take a look. I've heard others say they've worked on their coaches while parked at Pacific Shores. Will I be breaking any rules doing so?
Thanks,
Mike
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Mike,
The stater on a C12 should be on the right (passenger) side as you face the rear of the coach.
Steve
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Ok, I'll take my crawler on vacation with me, and spend some time under there. I know the oil breather exits in the rear right (engine nearest me when I stand back there) part of the engine, and I guess that stuff can go anywhere, and could coat anything so maybe my terminal is simply dirty.
Thanks Steve,
Mike
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I picked my coach up today. Chassis battery voltage was 13.3 and still the hesitation. I'll clean all the contacts first and if it persists, I'll delve deeper. But 13.3 should be adequate, correct? As Gerald said, may have some bad cells and not have the cranking amps behind it but when it has been run for a little bit, it will start without the hesitation.
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Adam,
13.3V would indicate a full charge so that is good. When you start the engine cold, the oil is thicker, and parts are not as well lubricated so the engine is more difficult to crank. That translates into higher current need to crank the engine and in your case that results in slower cranking speed. There should be no hesitation if all is well. Between warmer oil, lubrication, and some additional charging the cranking speed improves.
Later Ed
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Adam,
Since we have similar coaches (pre-2000) at which time, evidently, there were some changes made, I'll work on this issue as well, and let you know what I find. Please let me know what you find out as well, and we'll compare notes.
Thanks,
Mike
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Will do, Mike. Thanks everyone for the help and encouragement.
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Adam,
It is possible that you have cranking batteries that are just not up to the task of turning over a cold C 12, regardless of their age or charge state. That is one of the reasons that I told you to have your batteries checked for CCA (cold cranking amps). A cold C 12 will need in the range of 1600 to 1800 CCA to start it without hesitation.
I just looked at the Interstate Battery website and found four group 31 batteries that they make that will fit your coach as a cranking battery. They run from 660 CCA to 1000 CCA per battery. So a pair of the lower end cranking batteries will total to 1330 CCA when brand new, and they will probably cause a problem when cranking a cold C 12 from lack of capacity, even when new. However, a pair of the 1000 CCA batteries, at 2000 CCA, will crank a cold C 12 without hesitation, even after several years. All batteries are not created equal, and just because a battery is new that does not mean that it is up to the job.
Gerald
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Gerald
The batteries I have are rated at 950 cold cranking amps at 0 degrees. 1185 CCA at 32 degrees. They are almost 5 years old. Do you think they are at the end of life? I'll pull them out and have them tested.
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Adam,
I'll horn in and say, well, have 'em tested, but I had this problem BEFORE and AFTER the new batteries. I think I will change out that ignition solenoid in the wiring bay. My logic is, if it can suddenly wig out, ie fail completely and turning the key does nothing, might it also, as it fails, fail in some cases to immediately provide a load to the starter, thus the hesitation.
Anyway, if I do it, then I'll be doing it next week, and see if at least I am no worse off.
Mike
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Mike,
There is no chance that the ignition solenoid is causing the hesitation when cranking your engine cold. The only current to the starting circuit that goes through the ignition solenoid is to the starter solenoid, and if the ignition solenoid had a open, the starter would not engage instead of slowing down in speed. These are two totally separate, and unrelated conditions.
Gerald
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Gerald,
Perhaps it is true, but the problem I am experiencing, and I believe Adam is, as well, is NOT a slowing down of the starter motor. Its a temporary total cessation of anything, then immediately the starter turns and in my case immediately starts the engine. It's just that "dead space" or as Adam says, "hesitation".
Now, given that you know now that our problem is NOT a slowly turning starter, but instead, a hesitation, are you saying that it still couldn't possibly 100% be a failing circuit in this solenoid?
The sound is like HEAVY CLUNK (which sounds like the starter moved, but immediately stopped), then hesitation 1/4 to 1/2 second perhaps, then starter starts engine. As Adam said, it's more of an annoyance and he was going to ignore it, until I reported it, and no one else seemingly has had the issue but us.
Even if not many of us have experienced the problem in our coaches, most have probably experienced something similar in our cars. I did, in my jeep, and after several months in that case the starter eventually got replaced, so that may be the issue here as well.
Thanks,
Mike
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Mike and Adam,
The fact that you turn the key to the start position and then you sense hesitation has nothing to do with the ignition solenoid in the electrical bay. That is not a device that draws enough current to get any hesitation even if the batteries were a bit low in capacity, it simply makes or breaks contact to turn on the ignition buss. The starter solenoid and starter can certainly provide a hesitation when low voltage and low current being supplied. I'm sure this issue has happened before with cars you have owned when a failing battery or a low charge due to a failing alternator occurs. Those that have lived in cold climates have crossed that threshold of hesitation and lack of starting as battery capacity lowers due to the cold and engines become harder to crank due to thickened oil.
Five year old batteries as a diesel starting source is a bit long in the tooth. Over three years and you are doing well but it depends on the battery capacity to start with as Gerald points out. I have had several batteries fail in two years on my C12 and some will make it to 4 or 5 years. All of this depends on how deeply the battery was cycled during its life, the less deep cycles and the higher the charge state is maintained the more life you will get out of it.
Later Ed
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Tomorrow I will take the batteries loose, clean them up and take them to be tested. I have two new ones on standby should I need them. The new ones are 950 CCA at 0 degrees. Will those be adequate Gerald?
I did try the battery tie switch today. Held for 30 seconds as suggested by Ed (last time I tried it I just pushed it and turned the key) and it started without hesitation. Seems that would suggest a battery problem. I don't want want to spend $300 on batteries, but as my wife says, I can't take it with me! Standby.......
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"The new ones are 950 CCA at 0 degrees. Will those be adequate Gerald?"
Adam,
Yes, those batteries should be adequate for your coach.
Gerald
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Update. Replaced chassis batteries and no more hesitation. Thanks all.
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Adam,
Glad it is fixed, looks like all is well again. You did yourself a favor. That hesitation of the starter means current is going through the brushes to one segment of the armature winding and producing heat. The starter is designed so that each segment and winding sees a short duration of heating during rotation and the design can handle the heat load that is normally generated during cranking at the proper RPM. Even with that after 30 seconds of cranking they want you to take a several minute break to let things cool down.
Hesitation is hard on a starter and can shorten its life, so you may have saved yourself some trouble down the road.
Later Ed