normal operating oil pressure on C-9

[Stan Simpson]

Recently, while driving from New Orleans to Memphis, the 'check engine' light came on. I pulled over asap and consulted the manual. It said fluids may be low. I checked the trans fluid with the transmission shifter pad and it reported fluid level ok. I checked the oil and it was in operating range.

After that stop, it came on and went off several times in the last 75 miles of the trip. At 60 mph, the oil pressure read 50 psi on the gauge, and fluctuated from 48 to 58 on the Aladdin.

At start up, the oil pressure goes up to around 75 psi. What is the normal range while under way?

I have been parked on a concrete pad since last Wednesday, and I see nothing on the ground.

Help and suggestions would be appreciated.

Stan

[Joel Ashley]

Stan, if the engine coolant in the expansion tank gets below the sensor, the sensor activates the check engine lamp, as a number of other things can do.  But low coolant level is a common reason, so the first thing I'd do is check that your coolant is where it should be in the tank. A cracked and leaking hose below my tank caused a similar issue even when my coach was virtually new.

The tank on yours, if original, should be similar to mine - a white plastic one just behind the engine door, to the right of the engine and practically in front of your face, so it's easy to check.  The tanks are known to crack, but be sure to also survey all the hoses involved with cooling.  Many make long runs, especially from the tank to the radiator to the far left of the engine down low.  Check the radiator for evidence of a leak also.

I can't say off the top of my head what the oil pressure should be, but more than likely it's fine and the issue is low coolant.  The lamp going on and off intermittently is also indicative of coolant level low at the sensor, splashing around it on the road rather than fully covering the sensor as it should.

If tank or hose repairs are indicated, it would be a good opportunity to move to ELC (extended life coolant) if the coach isn't already using it.

Joel

[Stan Simpson]

Joel,

The coach has been sitting since last Wednesday night. I opened the engine compartment yesterday, and the coolant level was exactly at minimum. Should I be adding coolant at that level. Should it be around the middle of minimum and maximum when cold? I checked all hoses and fittings and examined the tank itself this morning. I see nothing amiss.

If I should have to add coolant, is it okay to mix ELC and regular coolant that I can buy anywhere? How can I tell if I have ELC?

Thanks,

Stan

[Edward Buker]

Stan,

With the coach being thoroughly cooled down, having the antifreeze at the min line is fine. Many times if you fill beyond that point it would just be lost due to expansion capacity not being sufficient to handle the extra coolant. If you do have to add it would be good to know what is in there and have a jug with you. If it is the traditional green it is safe to just get some standard Prestone. If it is purple it is likely Cat standard antifreeze. If it is red it is likely to be Cat ELC or another variation. Your other option for small amounts is to just add some distilled water if you do not have any other option handy. Up to a couple of quarts would not hurt anything but beyond that you would look to add back some concentrated antifreeze to get back to 50/50 mix.

If you check your coach manual and it has a monitor system like an Alladin you may have the means to read out an error code that will help sort this check engine light out.

Later Ed

[Gerald Farris]

Stan,
If you have Cat ELC (reddish color), only add ELC or water. Adding conventional coolant will necessitate a much shorter coolant change interval than having pure ELC. ELC has been lasting 7 to 9 years in coaches with the addition of one application of Extender, but conventional coolant or ELC that has been contaminated with conventional coolant only last 3 years. So if you do not have ELC, just add a couple of quarts of distiller water.

If the ambient temperature is in the 30 degree range with the coolant at minimum level, you should be OK. However, if the ambient temperature is in the 60 degree range, I would add a little as a safeguard against the sensor turning on the CEL (check engine light).    

Gerald

[Stan Simpson]

Excellent Gerald and Ed! Thank you so much. We are in rainy cold Memphis, and all have colds including the cats. I will get out there again when it warms up a bit on Monday.

Stan