Runs well cold, dies when it warms up - PeachParts Mercedes-Benz Forum

Togorashi · #1 08-24-2009, 06:28 PM

1981 300TD

Recently, my wagon has started to idle very rough and die if it idles for too long. Strange thing is that it purrs when I start it up and runs well until it gets to operating temps. Once it gets to about 90, it starts to lope and puff smoke.

I'm losing compression in a couple cylinders. #4 is at 232 and #5 is at 261. That test was done about 2,000 miles/1 year ago. It's not my primary vehicle and I don't drive it much. I know it's only a matter of time before the compression loss gets the best of me, but this seems like something else.

Any ideas?

Thanks.

Togorashi · #2 08-24-2009, 07:16 PM

Well, it's gone from bad to worse. Now it won't even start. It cranks, acts like it's going to start, sputters and then dies like it's starved for fuel or air. Changed the fuel filters and got the same results. What's next?

#3 08-24-2009, 07:20 PM

When was the last time you adjusted the valves? Tight valves can cause a loss of compression and might get worse when the engine is hot.

Togorashi · #4 08-24-2009, 07:29 PM

Quote:

Originally Posted by Craig

When was the last time you adjusted the valves? Tight valves can cause a loss of compression and might get worse when the engine is hot.

Valves were checked when the compression test was done. My mechanic said that they all looked good. He didn't adjust them. This makes me curious for a second opinion.

79Mercy · #5 08-24-2009, 07:30 PM

what color smoke?

#6 08-24-2009, 07:32 PM

If it's not valves, my next guess would be a head gasket or cracked head because you have low compression in two adjacent cylinders.

barry123400 · #7 08-24-2009, 07:34 PM

Do your own second opinion. They need checked that all or any individual valve clearance is not gone. Not set to actual recommended value initially. Just pull the valve cover and get a set of feeler gauges. Follow instructions in the archives.

You can impoverish yourself quite easily by paying for all services on an older car. It's bad enough costwise on a much newer car to use garages .

These older mercedes diesels are great learning or self teaching vehicles. This site is all you need to get started. Add tools as needed over time if you have none.

Togorashi · #8 08-24-2009, 07:36 PM

Quote:

Originally Posted by 79Mercy

what color smoke?

white

#9 08-24-2009, 07:38 PM

Quote:

Originally Posted by Togorashi

white

Was it using coolant?

Togorashi · #10 08-24-2009, 07:40 PM

Quote:

Originally Posted by barry123400

Do your own second opinion. They need checked that all valve clearance is not gone. Not set to actual recommended value initially. Just pull the valve cover and get a set of feeler gauges. Follow instructions in the archives.

You can impoverish yourself quite easily by paying for all services on an older car. It's bad enough on a much newer car to use garages sometimes.

You're correct. However, time is more precious than money to me. I've already sunk too much time into this vehicle. 100s of hours of work and still entropy seems to always be one step ahead of me. I'm about to just call it quits and get rid of the thing.

Togorashi · #11 08-24-2009, 07:41 PM

Quote:

Originally Posted by Craig

Was it using coolant?

Not really. I recently topped it off because it was a few ounces low. That didn't seem bad to me, considering that this has been the hottest summer on record in central Texas with almost every day over 100.

79Mercy · #12 08-24-2009, 07:50 PM

The reason your compression is low is because you have a blown haedgasket or a cracked or warped head. Usually when you have 2 cylinders low on compression right next each other its either a cracked/warped head or a bad headgasket.

Togorashi · #13 08-24-2009, 09:48 PM

Quote:

Originally Posted by 79Mercy

The reason your compression is low is because you have a blown haedgasket or a cracked or warped head. Usually when you have 2 cylinders low on compression right next each other its either a cracked/warped head or a bad headgasket.

I guess the part that I am curious about, is what changed? The compression has been low for a while. Maybe it was starting to fail and then it failed completely all at once? I would think I would be burning through more coolant and would see more smoke too.