Cracked head?Negative combustion leaktest

[ramjensen]

My '87 300d puffs white smoke and idles rough at cold startup. I tried the sniff test and couldn't smell sweet antifreeze in the smoke. I just bought a combustion leak test kit with a special fluid for diesels from toolrage. The test was negative for combustion gas in the expansion tank. Here are some observations:
1. It only happens when the car is cold.
2. If I hit the glowplugs twice it doesn't happen. I ohm tested my glowplugs and they tested fine.
3. I ran some lubromoly diesel hitest in my tank and it went away but came back with the next tank.
4. I have no bubbling in my expansion tank with the engine running.
5. My expansion tank doesn't have any black stuff in it.
6. I have replaced my injector nozzles with new bosio's and it made no difference in the smoky rough cold idle
7. When I got the car the turbo was nonfunctional due to a hole corroded in it and an exhaust leak where the manifold and head mate up. The car may have been run like this for a while. Could this have caused overheating and cracked my head?
8. When I replaced the turbo I also removed the exhaust manifold and had it resurfaced since it was warped. I had three broken manifold studs in the head which I had to drill and tap out. Does the warped manifold indicate overheating? Could I have cracked the head when I forced a tap into the stud holes?
9. The car runs kinda hot, 95C even in the dead of winter.
Any bright ideas? I will try the sniff test for antifreeze in the exhaust again tomorrow morning. I am also going to try running some diesel purge and diesel hitest. If this doesn't do it, could it be my glowplugs since hitting them twice eliminates the problem? Can they be bad even if they test fine with an ohmeter on the car? I tested the wires to them as well. Could I have a crack in my head which is too small to allow significant combustion gas in the expansion tank but will still allow some coolant to seep into a combustion chamber overnite? Maybe the crack is open when the engine is cold but as it heats up it closes as the metal of the head expands? Could it be just a bad head gasket? I will update after I try the sniff test and diesel purge. I sure hope it's not the head. My wife is already sick of my car, she calls it the mistress.

[sixto]

Do a search on how to do a simple resistance test on the glow plugs.

Does it hit 95*C while idling or while moving? How old is your coolant?

Sixto
93 300SD 3.0

[ray m]

Could this be caused by by worn valve seals. I think I heard something about blue smoke at start up caused by this. My son's car does this. Ray m

[yellit]

Glow plugs can test good with an ohmmeter and perform poorly under actual load....How long have they been in the car ?
Have you done a compression test to determine engine condition ?...This should be one of the first test...Do one test cold and then test again warmed up...see if the different cylinders change in pressures track each other....this may help to find a crack that is sealing somewhat after the metal expands like you said....You could also do the leak down test for more info...

You could also measure the water temerature with another gauge to see if you are indeed running hot....

[barry123400]

I assume you have done the morning after test. Thats where you check the upper rad hose to see if it is firm the next morning before starting. If so the head is cracked. Check the archives for a better decription. The lack of oil in the coolant expansion tank is a good sign though.

[captainmonk]

how cold is cold on the start up???????? if you glow twice and it doesnt happen and it is below freezing FORGET about it quit looking for trouble
BUT i'd be more concerned about 95 degree running temp coolant flush is in order electrical guages can have a lot of variabilty i like a guage right on the engine as back up

[Ken300D]

This seems to be very common with the 603 engines - they are "cold-natured" compared to the older all-iron 616/7 engines.

In the later 602/603 engines, the glow plug relay circuit was changed to keep the glow plugs on for up to 30-60 seconds AFTER the car starts. This solved the cold-nature problem.

If you step outside the car into the cloud of smoke, what you will smell is unburnt diesel - it will smell strongly of diesel. Not anti-freeze. The car just isn't warm enough to fully burn the diesel being injected, so it runs rough and maybe takes a few seconds for all cylinders to catch.

I can tell you from my experience that this behavior will persist through a complete change of all-new glow plugs. Since the task is pretty hard on these cars (most people remove the intake manifold) I recommend you not do that but in the future just replace the plugs that test bad.

So, your double-glow method is what I recommend. That, plus keeping your foot on the pedal a bit in the first few seconds after startup. Once you pull away from a stop and gently head down the road, the car will warm up and from that point idles fine.



Ken300D

[Brian Carlton]

Originally Posted by ramjensen

1. It only happens when the car is cold.
2. If I hit the glowplugs twice it doesn't happen. I ohm tested my glowplugs and they tested fine.

9. The car runs kinda hot, 95C even in the dead of winter.


Any bright ideas? If this doesn't do it, could it be my glowplugs since hitting them twice eliminates the problem?

Definitely. The statement of glowing twice and eliminating the problem is the key here.

Originally Posted by ramjensen

Can they be bad even if they test fine with an ohmeter on the car?

One or two are weak. The 603 needs all six plugs glowing nearly white hot for 30 seconds if you want a smooth start in the cold.

Originally Posted by ramjensen

Could I have a crack in my head which is too small to allow significant combustion gas in the expansion tank but will still allow some coolant to seep into a combustion chamber overnite?

Highly unlikely.

Originally Posted by ramjensen

Maybe the crack is open when the engine is cold but as it heats up it closes as the metal of the head expands? Could it be just a bad head gasket?

Your paranoia regarding the 603 heads is getting the best of you.



With regard to the 95C. operating temperature, the culprit is either the thermostat or the gauge. There is no other option.

The SD is running 90C. and climbs to 95-97C. under moderate load. I've got the same deal. The thermostat is brand new. An infrared sensor confirms that 95C. on the head is actually 87C. on the gauge. A gauge error of 7C. will really cause you to obsess about nothing.

[Mustang_man298]

Though I guess it could be possible under just the right circumstances you could have a tiny tiny crack that seals better when warm, I very seriously doubt it. In my experiience driving many cars over the years, both with steel and aluminum heads, when its cracked, its cracked, it doesnt go away when warm and you definitely know it's there. My car does the same thing, though not a 60x series, I have attributed it to cold weather, and a bad camshaft, I have yet to have my injectors balance checked as well, still has a very slight miss when warm at the right rpms you can feel, but mostly disappears after warmed up, just like yours. I agree with the others that you probably just have a cold weather issue, being that double glowing makes it disappear, that says a lot right there, as just double glowing would not produce enough heat to make a crack close. No oil in the coolant, no coolant in the oil, no bubbles coming out the radiator when running, no worries.

[mobetta]

yup, I agree. stop worrying and run it.
no wonder the wife calls her "the mistress", if you spend all your time obsessing over her I hope my wife doesnt see this thread.

good luck,mo

[aersloat]

You could also have a blown head gasket between the first cylinder and the chain gallery. This is a common location and the gaskets have been modified to improve durability at this location. This could affect compression in the first cylinder and make cold starts a bit rougher. I have the exact symptoms that you have with the rough cold starts. I found that using the block heater pretty much eliminated the problem as well. I do have lower compression in the first cylinder and I am pretty sure that my gasket is breached.

As far as running a bit hot, you might want to check your fan clutch. I was running hot last summer and upon checking it turned out that my fan clutch was toast. I installed the new plastic fan and new clutch and now I run cooler than I would like (my thermostat is probably bad too). If the thermostat was bad wouldn't it fail open and the car would run too cool, like in my case?

[ramjensen]

Thanks to all for the info and reassurance. I tried the sniff test a couple more times and definitely no antifreeze smell just unburnt diesel. I feel kind of dopey for not thinking of using my block heater, thanks for the suggestion.
Aersloat, the head gasket idea sounds like it deserves some investigation on my part. Regarding a compression test, is a regular compression test or a leakdown test better? Should I buy a cheap setup from harbor freight or have it done at a shop? I have read some about compression testing on this forum, and I will scour the forum again for info but would appreciate any input.
I now know these engines are cold-blooded by nature, but I want my car to start and run as it should and as well as it can. I'm sure that when in the proper tune and with everything functional these cars don't puke smoke and idle rough just because it's cold. I am relieved however that my symptoms don't indicate the dreaded cracked head. When I viewed some pics of cracked heads on this forum I almost wet myself.
I feel much better about the car now. As for the running kinda hot 95C, I have the citric acid for the flush, just haven't tried it yet. I tried checking the fan clutch by getting the car hot and hitting the emergency stop and the fan seems to stop pretty quick. Aersloat, is this test how you determined your fan clutch was gone? If so, how long did the fan freewheel before stopping? As I recall, mine stopped within a second or less of hitting the emergency stop. The thermostat is new. I want to get the car running cooler because I plan to get the AC functional for next summer and I know that will tend to get the engine running hotter.
Once again thanks to all for the help, this forum rocks and you guys are the best!