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Old 01-12-2005, 02:21 PM
Join Date: Jan 2005
Location: Northern Calif.
Posts: 4
Smoking 240D

I've got an 81 240D with a 78 engine, std trans. I got the car about 1.5yrs ago from a friend who bought the engine from a guy whos car was totaled by a dash fire. The engine had recently been rebuilt but don't know how many miles were on it when it was put into my car. It started immediately after the glow plug light went out and had no problems.

I was getting around 32mpg at first, but had problems w/ the radiator slowly going dry. Even w/full radiator, temp would rise (over 80C) during idle or coasting but would cool down (below 80C) when under acceleration. Also noticed oil being blown out of filler cap, got new cap, same thing. Could not find any obvious leaks or bad hoses. Put Bars leak in but problem slowly got worse. Also milage has dropped to around 25-28mpg, even after valve adj. Checked for water in oil but no foam on filler cap or water noticiable after oil change.

About 4 months ago, I began experiencing hard starts with rough idling but engine ran smoothly on freeway. Still had intermittant rough idle at stop lights or in heavy traffic.

For the last 2 months, I have the same problem with hard starting but now have white smoke. Smoke disappears after the engine warms up.

The car got hot yesterday, not into the red zone though, so I added water. I tried cranking the engine with the radiator cap off and a fountain of water shot out of the radiator, which lead me to believe there is a compression leak into the cooling system. I called a friend who suggested that the thermostat might be stuck. I removed it, and was able to press it open manually. Also noticed a slightly loose radiator hose. Tightened hoses and reinstalled thermostat and car seems to run smoother and cooler and doesn't idle as rough. Also doesn't seem to overheat now but still have problem with hard start and white smoke when engine is cold. Have driven 40miles without overheating but major test will be tonight when I commute 75miles home.

I know gas engines well, but am still learning to wrench on diesels and am not confident of my diagnostic skills when it comes to them, so my question is: Could I have a combination of problems? If I fixed the water leakage by tightening the hoses, or possibly loosed a stuck thermostat, could the white smoke be from a bad injector? Or do the symptoms indicate a bad head gasket or head?

Sorry for the lengthy diatribe, but I felt the more info you have, the better you can evaluate my question.

How hard is it to do a DIY head gasket replacement for a diesel rookie?

Thanks a lot

Last edited by steviek; 01-12-2005 at 02:43 PM.
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Old 01-12-2005, 05:42 PM
Registered User
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
My 240 does the same thing on the temperature.. even a slight long hill and you can see it change.... Others have also reported this.. so unless you are really overheating now that you have fixed the hose leak I would not worry about it...
Do you have any literature for your car ? Like the shop manual ?
It sounds like a gradual loss of efficiency has happened... but you are still getting better miles per gallon than I am ( but I only paid $500 for my car )...
So I suggest as a cheap first effort... which may surprise you for its nice effects... that you spend $20 to get two bottles of Diesel Purge.. and get new filters for your engine compartment... and use the DP according to instructions...
Then report back and we can go from there...
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Old 01-12-2005, 07:59 PM
bullwinkle's Avatar
manic mechanic
Join Date: Jun 2004
Location: cincinnati
Posts: 377
I'd borrow a cooling system pressure tester and check for leaks-the white smoke could be a coolant leak into a cylinder-the rough idle may also be a symptom of the same thing-a compression test(with a diesel compression tester)might not be a bad idea either.
1982 300DT 190K (Diesel Purge + synthetic oil=smoothness at last!!!)
2004 Ford E-350 6.0 L PSD 227K
2006 Dodge Ram 3500 SRW HO Cummins 4X4 48RE 42K (brute force tow vehicle)
2005 Scion xB wife's rolling pop can
1993 GMC Sierra C3500 6.2 142K

Last edited by bullwinkle; 01-12-2005 at 08:00 PM. Reason: didnt see valve adj.
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Old 01-12-2005, 10:40 PM
whunter's Avatar
Join Date: Dec 2003
Location: Metro Detroit, Michigan
Posts: 17,370
Unhappy Correct diagnosis.

Bad head gasket or cracked head...
RE: I tried cranking the engine with the radiator cap off and a fountain of water shot out of the radiator, which lead me to believe there is a compression leak into the cooling system.
Stop driving it, or you will scrap it...
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1983 300D
1984 190D
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Old 01-12-2005, 10:51 PM
JimmyL's Avatar
Rogue T Intolerant!!!
Join Date: May 2004
Location: Sunnyvale, Texas (DFW)
Posts: 9,675
Since I also am experiencing some of your symptoms, does your smoke quickly dissipate or hang around for awhile?
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
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Old 07-18-2005, 01:31 PM
Veggie Power
Join Date: Mar 2005
Posts: 48
I'm also having the same problem with my 1980 300SD. Hard starting hot or cold, white smoke that disapates, then smooth running....
1980 300D (Luna)
1980 300SD (Sunny)
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Old 07-18-2005, 02:59 PM
83mercedes's Avatar
Ign'ance be blis
Join Date: Mar 2005
Location: Gainesville, FL
Posts: 306
Why don't you get an oil analysis done to check for coolant contamination?

Pressure check your cooling system; see if still contains pressure after sitting overnight from last time the engine ran.

Temperatures over 80C slightly aren't too concerning, but coolant loss, power loss, fuel efficiency loss, and white smoke combined are. Typically indicative of a head gasket or head failure.

"I would rather be ashes than dust!
I would rather that my spark should burn out in a brillaint blaze
than it should be stifled by dryrot.
I would rather be a superb meteor,
every atom of me in magnificent glow,
than a sleepy and permanent planet.
The proper function of man is to live, not to exist.
I shall not waste my days in trying to prolong them.
I shall use my time."

-Jack London 1876-1916

1983 300CDT (running WVO since 12/05)
1981 300SD (parts car)
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