1987 300D odd symptoms.... - Page 2 - PeachParts Mercedes-Benz Forum

riethoven · #16 10-16-2006, 04:41 PM

Quote:

Originally Posted by Marcb

Well, I'm still investigating this a bit further. My wife told me that she's seen a small "trail" of water the past few weeks every time she backs up the car. That tells me that it must have been pushing water out of the recovery/expansion tank while on the highway or something. I'm not sure.... One more update - I'm also told that while trying to start the car it wouldn't start properly a couple of times. After glowing, the starter would engage and the car would act like it was "frozen"... i.e. wouldn't turn over, just dim the dash lights. After the engine was rotated via the belt a couple of times, it would start and run just fine. I hope this isn't another "bad" sign and simply a starter getting old! Any more thoughts?

I have a spare 603 engine on the workbench with 120k miles on it (per the seller) and I don't know if I should simply swap the 2. It also has a 14 head on it and I'm having trouble deciding. Heck, I don't know if I even have a real problem yet! A new 22 head is $1800 plus the cost of new lifters, etc. Please feel free to share any thoughts you might have. I really appreciate it! You guys are great!

I have a 1987 TD with the 603 engine and the head is cracked. I bought it that way. Through my research I found that there are Spanish made aftermarket heads that are around $800. I got this info from Mark DeGroff who has a few of the heads in service with no problems.

Marcb · #17 10-16-2006, 04:54 PM

Wow, that sounds like a bargain compared to what I've been seeing. I really hate to pull the head off only to find I need to repeat the job IF the orig #14 head cracks. (It may already show cracks, I'm not sure).

Well, I checked with Mark and he said he has other sources for these heads but didn't elaborate just yet. After describing my "symptoms", he thinks I'm definitely needing *at least* a head gasket....

psfred · #18 10-16-2006, 06:58 PM

Pressure test cooling system, replace radiator cap, and replace the starter, sooner or later it's gonna lock up completely.

VERIFY that you do not have a cracked head before replacing the starter -- check for coolant in the oil. If the head is cracked, and water is collecting in a cylinder, sooner or later you are going to bend all the rods by hydrolocking it!

Peter

Marcb · #19 10-16-2006, 07:43 PM

Thanks for the tips PSFred. I think I'm going to let the car sit until I can find a suitable head as a replacement. I wish I could find a yard willing to trade the entire 603 eng assy for a good used head. I have so much of the history on this engine an it's been fed synthetic oil for many, many miles! And, it doesn't use much oil between every 5k change.

Marcb · #20 10-18-2006, 02:21 PM

Any more thoughts... the cooling system pressure test was not conclusive. It must be a *slight* leak as they couldn't tell me with 100% certaintly that it has a cracked head. Do you guys think I might get lucky and simply have a failed head gasket? What is odd, is that the engine runs very well but does have some noticeably louder lifter noise (this is odd as it only did this rarely about 200 miles ago). Also, the upper radiator hose is soft when cold but is hard almost immediately after a cold start. It seems as if there is air trapped in the cooling system. I'm afraid this "air" is actually combustion gas trying to escape. You can literally watch the recovery/expansion tank level adjust itself as the air is maniuplated in the system. At this point in time, I believe the head must come off. I think I'm going to send in some oil for a sample. Unfortunately, I had just changed the oil and it only has about 200 miles on it. Would this conclusively provide enough time for the fluids to mix? The oil is still very clean and I can't see evidence of water in the oil or vice versa! This definitely isn't your typical 603 cooling/head problem. I just can't imagine a new radiator cap would fix anything. And.. I still can't account for the white whispy smoke that rises out of the coolant expansion tank when the engine is idling... even after you start it cold. I guess I can't assume it is boiling coolant and I can't imagine that trapped *air* would look whispy. Funny enough, it reminds me of blow-by on a much smaller level. I've never seen anything like it and it kind of trickles out of the filler. Any thoughts from the 603 "gurus"?? I just hope that replacing this head gasket... (thinking positive here) will allow this thing to run as nicely as it has for the last 60k miles. I'm thinking I may pull the engine/trans together so I can try and R&R the front pump seal on the trans. Any tips of advice with this job?

Casey, if you're out there, please feel free to drop me a line or PM as well. I'd love to chat with you about my 300D since you're local. GSXR, any thoughts from your experience with these engines and the head?

TIA,
-Marcb

Marcb · #21 03-06-2007, 03:26 PM

Well, it is confirmed that the original #14 head was cracked on the car. The headgasket was still in good shape but apparently the crack was allowing combustion gas into the cooling system. Odd thing, however, I have a known good radiator cap, no verifiable leaks and it never exhibited any rock-hard hoses when cold. It would pressurize them almost immediately when started cold but they felt normal when it sat overnight. I'm hoping the car will be back on the road soon. Just FYI...

psfred · #22 03-06-2007, 03:54 PM

First you must verify that you don't have a coolant leak -- the lower radiator hose is hard to see, crawl under and check. A pressure test is in order, as well as a visual check of the water pump. The o-rings on the heater core can leak, too -- coolant will drip off the underbody panel just like AC condensate does, look there.

Steam is normal with the coolant low -- a bad head gasket or cracked head will cause the coolant tank to be under considerable pressure cold.

The starter will eventually lock up as the bushing go bad, this is normal -- if coolant is leaking into the cylinders, it won't turn over by hand any better than it does with the starter.

I just finished the head gasket job on mine, blown out.

Peter