Too Much Engine Oil?

[Gary Winzenburger]

We just got back from our first, long trip with our 1997 Marquis with 3126 Cat motor. I checked the oil every time we broke camp. Once we got home, I let the coach sit overnight in our front yard to unload it (leveled) and found it low on oil the next morning. I added over 3 quarts of oil to where it showed full on the dip stick. I then moved the coach app. 100 feet to it's parking pad and again releveled. I checked it again the next day, and found the level way above the full mark on the stick - I think by about 3 quarts!! What should I do now?? Do I drain some out, or should I not worry and drive it again? Any thoughts would be appreciated.

[Edward Buker]

It would be good to know which is the right measurement based on true level. Not sure if a real 2-4ft level on the floor would help. I can only speak for a Cat C12 and I know that mine was filled to 40 quarts for quite some time given the dipstick was never calibrated. I spoke with Cat about that and they said that was fine given the size of that motor. They asked about any excessive oil coming from the engine breather vent coating anything which it never did. That was about a 10% overfill in my case.

Later Ed

[Karl Welhart]

Gary,

I would drain enough oil to bring the oil level back down to the full mark on the dip stick.  Then I would recommend that you re-calibrate or really confirm the amount of oil in your crankcase. Basically, to verify your dipstick mark, drain all the oil and filter.  Replace with new oil filter, fill with 27 quart of oil.  Start and run the engine until warm, then wait overnight before checking the level on your dipstick.  

Remark, if necessary, your dipstick for the full level.  Cat has this procedure on their website if you need more details.  My procedure also assumes you have the deep sump and not the shallow sump.  Additionally, it is better for a 3126 to be a little low on oil then to overfill.

Good luck,

Karl

[Gerald Farris]

Gary,
The first question is, are you sure what is really the full mark on your coach? If the dip stick has not been recalibrated, you do not know what is actually full.

The next question is are you positive that your coach has a 3126 engine? Every 97 Marquis that I have seen was equipped with a C-12. If your coach has a C-12, the 3 extra quarts should be no problem. On a 3126 it is a little more of a concern, but I would not drain the 3 quarts out unless it starts blowing oil out the breather tube.

The course of action I would take is to verify which engine you have with the local Cat dealer, or a knowledgeable truck shop who knows the difference. Change the oil when necessary, and calibrate the dip stick.

After you know where the correct full mark is and where the add mark is, only add oil when the coach is truly level and only when the engine oil level is at or below the add mark. The add mark is one gallon low, so you never need to add less than one gallon. Do not top off the engine with one or two quarts.

Gerald  

[Gary Winzenburger]

Hi Gerald,
I've double and triple checked the ID tag on top of the motor because of your earlier comments regarding this. Yes, I'm fairly sure it's a 3126 since that's what the ID tag shows located on top of the motor (built in 1996). I have papers that state Gillig built the chassis in Nov. 1996 and the ID tag located near the entrance door states the Marquis was built by Beaver in January 1997. The motor is mated to a 1996 Allison MD3060 tranny, not the 4060, which, I believe was used with the C-12. Does that make sense? With it only having 81,000 miles, I don't think the motor and tranny were replaced, but I'm not sure. So, now I'm really confused! I'll take the motor ID number to CAT and have them do a little research to confirm one way or the other.

The dip stick has marks where the operating range should be, so that's what I've been going with after making sure the coach is level. I feel more comfortable about not worrying too much about the 3 quarts. It performed very well getting good MPG for the size and weight of the 40' coach!
Gary

[Gerald Farris]

Gary,
The original markings on the dip stick may or may not be accurate. The dipstick tubes on almost all engines were made-up by the chassis manufacturer to fit the engine access that is available. Therefore the dipstick that is used does not always match the tube length which makes for an inaccurate measurement for oil level.

There are dip stick calibration instructions in your engine manual. The instructions are simply with the coach perfectly level, drain the oil, and replace the oil filter dry. Then you install the correct amount of oil less one gallon. This is were you need to know the correct engine specifications to determine the proper amount of oil. C-12s use a total of 9 gallons so you would install 8 gallons and the 3126 will use a different of oil that will depend upon which oil pan is used on your engine. Cat can take your engine serial number and tell you all of this information. After you have installed the correct amount of oil less one gallon, start the engine and let it idle until you have oil pressure. Then turn it off and let it set for 5 minutes to allow for oil drain back to the pan. After 5 minutes check the dipstick, and if the oil level is not at the add mark, remark the dipstick for a new add mark. Then add the remaining gallon of oil and remark the full mark if necessary.

Gerald  

[Edward Buker]

If you call Cat with your engine serial number they will conform for you what engine you have if you still have questions. The comments on the dipstick and calibration mean that you cannot even be sure that the dipstick is correct, if it has never been calibrated. Cat, when they confirm your engine can tell you the oil capacity. Do not be surprised if you use a little more oil if you are overfilled.

Later Ed