E-Class (W124) 1984-1995: E 260, E 300, E 320, E 420, E 500 (Includes CE, T, TD models)

300te compression test for oil loss?

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Old 03-19-2009, 07:16 PM
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300te compression test for oil loss?

1989 300te...losing oil..maybe smoky exhaust (hard to tell - still cold out).
In the old days (1960's) we did compression tests on our cars. Kinda fun, informative...usually scared us with the #'s.
What is the procedure for doing one on the 300te? Specifically!
This is what we 'used to' do:
1. remove all plugs
2. screw tester in #1 plug hole
3. crank 4-5x, write down #, repeat.
4. do this for all cylinders.
To test for rings, we would squirt some oil into the plug hole and repeat test...if # is different, possible ring problem
---Is this the method? Do I crank 3-5x? What are 'normal' #'s? How do I 'really' check for ring problems? How much oil do I inject into the top of the cylinder?
Thanks.
Old 03-19-2009, 08:33 PM
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Compression won't give you an indication for oil loss.

What are the condition of your spark plugs? How much oil are you burning through?
Old 03-19-2009, 08:56 PM
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Originally Posted by ps2cho
Compression won't give you an indication for oil loss.

What are the condition of your spark plugs? How much oil are you burning through?
I will pull the plugs this weekend...I lose about 1 quart every 200 miles or more. I am not really sure as I haven't measured the times between fills. I will take notes now. PS...your 300 looks terrific.
Old 03-19-2009, 10:04 PM
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1992 300TE 4matic wagon
Are you sure you're burning the oil? I ask this because these cars are notorious for a warped head & companion leaking head gasket. Much has been written on that in here. It's very possible that your oil is leaking down the side of your engine from the head gasket and/or back into your coolant. Check the appearance of your coolant-yellow monkey looking pooh means oil in there for sure. You can buy a block tester at NAPA and do a test on the coolant itself to be sure if there is oil in there.

Presently, while I'm waiting for the weather to get decent to repair this, my 300TE 4matic wagon is not only leaking oil into the coolant, but also down the side of the engine at about the rate you mention in your original post. You can run like this indefinitely, but oil inside your coolant hoses will eventually break them down and possibly rupture.

You can get great compression readings even with a faulty head gasket on these cars. I did a leakdown test in the beginning and got great percentages for a car with over 200K. However, the engine has to be running and at normal temperatures for these faults to occur....so that will rule out your normal compression check and leakdown test for a leaking head gasket.

If you really do have bad rings, then a normal leakdown test will suffice...much better than just a simple compression check. These cars engines are not made with voodoo, but they do have some minor quirks. I would bet that you have the head gasket issue, because these engines go a long time without ring trouble-with a complete head rebuild at around 200K (providing your head gasket doesn't leak prior), the 103 engine is design capable of 450K.

Kevin

Originally Posted by AlanS
1989 300te...losing oil..maybe smoky exhaust (hard
to tell - still cold out).
In the old days (1960's) we did compression tests on our cars. Kinda fun, informative...usually scared us with the #'s.
What is the procedure for doing one on the 300te? Specifically!
This is what we 'used to' do:
1. remove all plugs
2. screw tester in #1 plug hole
3. crank 4-5x, write down #, repeat.
4. do this for all cylinders.
To test for rings, we would squirt some oil into the plug hole and repeat test...if # is different, possible ring problem
---Is this the method? Do I crank 3-5x? What are 'normal' #'s? How do I 'really' check for ring problems? How much oil do I inject into the top of the cylinder?
Thanks.
Old 03-19-2009, 10:22 PM
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1994 E320 (current)
Originally Posted by AlanS
I will pull the plugs this weekend...I lose about 1 quart every 200 miles or more. I am not really sure as I haven't measured the times between fills. I will take notes now. PS...your 300 looks terrific.
Check the coolant and see if it looks like a foamed up latte. If so your oil is pushing into your water jacket.

At night get a buddy behind you about 2 or 3 car lengths. Sit and idle at a stop for a minute or so and then punch it. Watch in your rear view for smoke in the headlights of the car behind you.

Like shep said look for leaks in the head gasket. Are you leaving any puddles or do you smell oil. I just completed a head gasket replacement on my 94 320 and it was pushing about 2 quarts a week. Look at the corners of the head on the passenger side. Often times the oil leaks while driving and then when you stop the leaks are minimal and don't leave big puddles. Let us know what you find.
Old 03-19-2009, 10:52 PM
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1992 300TE 4matic wagon
Ditto on that....mine is VERY well housebroken when parked. Well...it couldn't exactly be parked on someone's painted garage floor, but I don't have that luxury.

GED, how's your beast running after the head gasket repair?? Idle, MPG, power etc...

Kevin


Originally Posted by GEDaggett
I just completed a head gasket replacement on my 94 320 and it was pushing about 2 quarts a week. Look at the corners of the head on the passenger side. Often times the oil leaks while driving and then when you stop the leaks are minimal and don't leave big puddles. Let us know what you find.
Old 03-19-2009, 11:19 PM
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1994 E320 (current)
Originally Posted by Real1shepherd
Ditto on that....mine is VERY well housebroken when parked. Well...it couldn't exactly be parked on someone's painted garage floor, but I don't have that luxury.

GED, how's your beast running after the head gasket repair?? Idle, MPG, power etc...

Kevin
Doing great. I have only given it 70% throttle to this point (wanted to make sure gasket seated and expanded well) but it has been 5 days now so tomorrow she gets red line -500. There is no oil leaks at all to this point. I need to replace a coil that is causing a little bit of power loss through the timing advance stage 2000rpm - 5200rpm. After that she is a dream. The car had plenty of power before it just had the Hershey squirts. I am replacing a leaking trans line coming out of the radiator tomorrow then its on to the front suspension. I am thoroughly impressed with the 3.2 twin cam. When it advances the timing it feels like a 5.0 mustang and doesn't want to stop accelerating well past 100mph. I can't imagine what the 500 feels like.
Old 03-23-2009, 02:49 AM
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1992 300TE 4matic wagon
Cool....sounds like everything went well for you. Yeah, that twin cam 3.2 is a great design-I'm always looking at the cutaways for it.

I'm gonna turbo the 3.0 single cam after I replace the head gasket, suspension parts, brakes etc. I read somewhere that the faster you go, the less the power steering actuates. Anyway at speed, it sure feels like rack and pinion. These cars are a dream past 100mph...they really have that 'safe' feel. On 'the road trip' last summer, my car had no problem hitting 140mph in NV/NM a number of times. How much more it has than that, I'm not sure (if any).

Kevin


Originally Posted by GEDaggett
Doing great. I have only given it 70% throttle to this point (wanted to make sure gasket seated and expanded well) but it has been 5 days now so tomorrow she gets red line -500. There is no oil leaks at all to this point. I need to replace a coil that is causing a little bit of power loss through the timing advance stage 2000rpm - 5200rpm. After that she is a dream. The car had plenty of power before it just had the Hershey squirts. I am replacing a leaking trans line coming out of the radiator tomorrow then its on to the front suspension. I am thoroughly impressed with the 3.2 twin cam. When it advances the timing it feels like a 5.0 mustang and doesn't want to stop accelerating well past 100mph. I can't imagine what the 500 feels like.

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