300D engine problems
Thread Starter
Newbie
Joined: Jan 2009
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123 300D - at least I own one
300D engine problems
I am new to this and to the cars... did I buy foolishly?
300D, low compression between cyl 4 & 5. Mechanic says he hears no blow by between the cylinders...
Car has 80,000 miles, new radiator? Was it cooked? We don't know what is happening with the rings in those cylinders, they think they may be frozen because the car had sat.
Question is now is this realistic and what is the fix?
Can I pull the pistons from the lower end and redo the rings, will there be scoring?
Should I just drop another engine into it?
Or is this one that is too far gone... se la vie... Or is it for sale... rest of the car is in good condition and no rust so...
Best regards!
300D, low compression between cyl 4 & 5. Mechanic says he hears no blow by between the cylinders...
Car has 80,000 miles, new radiator? Was it cooked? We don't know what is happening with the rings in those cylinders, they think they may be frozen because the car had sat.
Question is now is this realistic and what is the fix?
Can I pull the pistons from the lower end and redo the rings, will there be scoring?
Should I just drop another engine into it?
Or is this one that is too far gone... se la vie... Or is it for sale... rest of the car is in good condition and no rust so...
Best regards!
MBWorld Fanatic!
Joined: Jan 2007
Posts: 1,152
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From: Sydney, Australia
190D 2.5 (x2), 190E 2.6, W202 C240,W202 C43 (C55), W210 E55, W212 E250CDI
Check and adjust all the valve clearances before diving in too deeply. This is a very basic service item that gets forgoten and can cause anything from low pwer, hard start, smoke, uneven running, high fuel consumption.
Check it first then recheck the compression.
What are the figures for dry and wet compression?
Check it first then recheck the compression.
What are the figures for dry and wet compression?
Thread Starter
Newbie
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123 300D - at least I own one
Compression
Thanks for the reply... compression in 1 - 3 is up around 400 psi, 4 and 5 are at 120 - 140... I am not sure about the difference between wet and dry...
Could this be valves? It did overheat quite quickly on their test drive...
M
Could this be valves? It did overheat quite quickly on their test drive...
M
MBWorld Fanatic!
Joined: Jan 2007
Posts: 1,152
Likes: 29
From: Sydney, Australia
190D 2.5 (x2), 190E 2.6, W202 C240,W202 C43 (C55), W210 E55, W212 E250CDI
"dry" compression is a normal compression test.
"wet" is when you but about 10-20ml of oil in the cylinder and then running the compression test. If there is a large change in the readings then the piston rings are sticking/worn. If there is no or little change then the leakage is from the valves/head.
Have you checked the valve clearances yet?
If it's overheating then you really need to get that sorted beofre it does more damage.
"wet" is when you but about 10-20ml of oil in the cylinder and then running the compression test. If there is a large change in the readings then the piston rings are sticking/worn. If there is no or little change then the leakage is from the valves/head.
Have you checked the valve clearances yet?
If it's overheating then you really need to get that sorted beofre it does more damage.
Thread Starter
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123 300D - at least I own one
Engine
The mechanics thought the overheating was connected to the compression in the last two cylinders. The car has a new radiator.
So what you are saying is that they may not be related to each other while this is exactly what the mechanic is trying to tell me.
The car is off the road until I figure something out...
Its a bit of a shame too,the car is quite clean!
M
So what you are saying is that they may not be related to each other while this is exactly what the mechanic is trying to tell me.
The car is off the road until I figure something out...
Its a bit of a shame too,the car is quite clean!
M
Thread Starter
Newbie
Joined: Jan 2009
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123 300D - at least I own one
dumb and dumber
I feel like Jim Carey in Dumb and Dumber...
So you're saying there's a chance...
So after all of this, it could still just be the valves?
REALLY?
Like I said I am new at this diesel stuff... All I know is from the back seat of an old 123 in central european taxis!
Wish me luck? Or could someone confirm that this really could be it.... before I spend the money and find I have tuned up a bad engine?
M
So you're saying there's a chance...
So after all of this, it could still just be the valves?
REALLY?
Like I said I am new at this diesel stuff... All I know is from the back seat of an old 123 in central european taxis!
Wish me luck? Or could someone confirm that this really could be it.... before I spend the money and find I have tuned up a bad engine?
M
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MBWorld Fanatic!
Joined: Jan 2007
Posts: 1,152
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From: Sydney, Australia
190D 2.5 (x2), 190E 2.6, W202 C240,W202 C43 (C55), W210 E55, W212 E250CDI
As long as you have some spanners, sockets and feeler gauges then it'll cost you nothing to check. I'm sure someone here has a link to a adjustment guide.
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Super Member
Joined: Jun 2008
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From: Bay Area, CA
09' E320
Your mech's think the head gasket is blown causing loss of compression AND the overheating.
Poor valve adj can cause loss of compression; it should be checked before the head come off. Overheating can be the result of many other non-related issues.
Poor valve adj can cause loss of compression; it should be checked before the head come off. Overheating can be the result of many other non-related issues.
