67' M38A1 CDN2 oil control issue.

[lesk]

Hi...I am new to this site and have many questions as to my newly purchased M38A1 CDN2. It was rebuilt (as motor pool jeep) by a retired military mechanic at one of the CAF bases. He gave me dozens of pics of the rebuild but showing no detail. I have also called him several times to verify certain things. The jeep was completed in 2012. I have about 2000 kms on the jeep and it consumes oil (Rotela T 15w40) at a rate of about 1 liter/500-600kms.
The rebuilder said that he replaced the compression and oil control rings and all bearings. The jeep starts well & runs smooth & quite.
So, The jeep does not smoke at all on start or on acceleration at operating temp. The plugs show no oil fouling the insulators showing a brown-grey insulator, both upper & lower fording valves are present but open, the PCV valve is clean and rattling, oil leaking is 1-4 drops per day usually after a drive from the rear mail and front crank seal.
How is the oil disappearing?

Also, the engine temp gauge (tested ) shows 180-185F at operating temp. I have a new 3 pulley water pump, the rad fluid is new and at 50/50, the rad has been cleaned/flushed and the cap is 4 lbs.....is 180-185F normal?

Thanks in advance,

lesk

[wesk]

1 quart in 400 miles is not all that bad so long as the plugs are not fowling and there aren't large puddles. I would re-verify those fording valves are actually fully open. With the F134 the intakes will feed oil past the guides readily.

I would assume that a strict and frequent operation schedule was not used to insure a proper seating of the rings. Considering a good break-in happens between 500 & 800 miles the first year of the rebuild I would guess that 1200 total miles in 5 years since the overhaul did not result in a good seating of the rings.

A compression check and leak-down check is very recommended here.

[lesk]

Hi Wesk...thanks for the reply....I was told that the jeep sat for 2-3 years as the rebuilder was trying to sell it. It was first sold in 2015 and that person put 600 miles on it to early 2017....that is who I bought it from in July of this year but he gave me all the rebuilders pics and contact info...I have put on 600 miles and have consumed about 1.5 quarts of oil. From what I have assumed from the character of the person I bought it from maintenance was not his priority.

As per my 1st post, last question, the jeep runs at 180-185F (all summer) even though I replaced the leaky water pump and had the rad flushed & cleaned....is 180-185F normal operating temperature?

Regards,

lesk

[wesk]

As per my 1st post, last question, the jeep runs at 180-185F (all summer) even though I replaced the leaky water pump and had the rad flushed & cleaned....is 180-185F normal operating temperature?

Some printed references with the answer to that question are in the TM 9-8012 page 25, 29, 86, & 141/142.

As for the oil consumption see pages 77.

Before launching a troubleshooting spree on the temp indication I would suggest first verify the accuracy of the gauge/sender.

simple start is to immerse the sender in a pan of water with wire # 33 still attached. Suspend the sender in the water so it does not touch the sides and bottom of the pot. Add a ground wire from the senders body to the engine block. Now you can do a detailed check by adding an accurate thermometer to the same pot. Slowly heat the water with a propane torch while you observe the thermometer reading and have a helper sit in the jeep with the master switch on and have this helper announce the reading of the gauge every 5 degrees while you monitor and compare that reading to the thermometer. Or you can just wait for the water to boil and check that the gauge reads 212 degrees.

If these test results indicate a gauge error then proceed to the Instrument Troubleshooting service bulletin TB 9-2300-228-20.

All of these TM's and TB's if you do not have them are available free in PDF format right here on this web site's "Downloads Page".

I was told that the jeep sat for 2-3 years as the rebuilder was trying to sell it. It was first sold in 2015 and that person put 600 miles on it to early 2017....that is who I bought it from in July of this year but he gave me all the rebuilders pics and contact info...I have put on 600 miles and have consumed about 1.5 quarts of oil. From what I have assumed from the character of the person I bought it from maintenance was not his priority.

This poor treatment of the jeep explains your oil consumption. I doubt very seriously that a proper seating of your rings ever happened under this set of circumstances. Follow the suggestions above. I would not be surprised if you had to re-hone your bores and run a correct break-in regimen.

[4x4M38]

Wes,
Is 1 quart in 400 miles acceptable for a jeep?

I would be concerned if my F150 used that much oil.
It seems like a lot to me.

Just trying to understand.

Tks,

[wesk]

Did I say "Acceptable" ???? The best way to understand is read the entire thought!

[oilleaker1]

A compression test is the first thing to check. If your compression rings are broken or too large a end gap, the oil can be literally pushed out of the crankcase, or recirculated into the combustion chamber and not show smoke. Been down this road. Since it's not smoking out the exhaust, I would think the rings are seated, but you may have blow by. John

[45auto]

Don't overlook your thermostat---Since there is some question of the quality and/or depth of work done, it wouldn't be a bad ideal to check it. If your engine has a 180 degree thermostat--it would run round 180-185. Its not so hard to check, you will need to drain the water level below the head--remove the three bolts holding the water hose neck to the head and it will be sitting in the head. There will be a number stamped on it indicating what degree range it is. If it looks like it has been in there awhile, go ahead and replace it with a quality made thermostat. you will have your choice of 160, 180 or 190 degree range. if you want it run cooler, go with the 160 degree thermostat. Also, you will most likely need a new gasket. Both the thermostat and gasket should be available at your local auto parts store.

[4x4M38]

No Sir. Acceptable was my word.

[lesk]

Thanks to Wes and 45Auto for the tips....when it gets warmer I will test for engine compression. I must say not withstanding the oil consumption, the engine is quite and runs very smoothly.

45Auto....after I bought the jeep in early July I took apart the thermostat housing to replace what I thought was a poorly functioning thermostat (it was running at 120-130F) during the summer months....I discovered that there was no thermostat....it was running open all the time. I called the rebuilder and he told me that as per his military units doctrine he was told to run all jeeps with an open thermostat. After the call, I installed 160F thermostat....now it runs at 180-185 during the summer months...I was told that this is not a normal operating temperature.

Regards to all,

lesk

[wesk]

Have you read the written technical references I referred you to yet? They will make it clear what is normal and what is not.

Thermostats are tested in a pot of heated water while observing their opening and closing points as well as their full open points. A 160 degree thermostat should start opening between 148 & 155 degrees and be fully opened by 160 degrees just as a 180 degree thermostat should start to open 158 to 175 degrees an be fully open at 180 degrees.

During hot months or when the engine is being worked unusually hard at low speeds the radiator can reach a point where it can't maintain the temp below the top limit. Under those conditions a + 10 degrees or more would not be uncommon.

[lesk]

Hi Wes....I do not have the TM-9 manual so I was not able to read the references. I have tested my 160F thermostat (as per this thread)and it does open between 155 and 165F....also tested my temp gauge....still not sure why my the jeep runs at 180-190F at operating temp?

lesk

[4x4M38]

Lesk,
All the manuals you need are available here free to download at the top left under Downloads.

Take care,

[wesk]

And is your temp gauge dead nuts on? Download the free manuals and see how your tests measure up.