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  #1  
Old 04-10-2020, 08:53 PM
JSR JSR is offline
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Question Coolant in oil, 1976 240D Manual

My power steering pump replacement has morphed, vacuum pump rebuild, water pump, front seal... I'm pretty torn down right now, most everything off the front of the engine, radiator out, etc.

My 1976 240D with about 112,000 miles was running great before I parked it a year ago, no symptoms. As part of the above, I thought I would remove the oil pan and clean it out; about 16oz. of coolant came out of the drain plug, then the oil.

I have gone back and read most of the threads about head gaskets, chasing down leaks, etc. I'm not a position to pressure test the system, I was going to just roll into replacing the gasket.

Before I do I wanted to ask all of you if I might be missing something?

Any thoughts about the job ahead of me are very much appreciated.

Thank you.

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  #2  
Old 04-10-2020, 10:57 PM
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If the freeze protection of the coolant was sufficient for the climate then it's probably the head gasket. May want to have the head checked for cracks.

Good luck!!!
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Old 04-10-2020, 11:18 PM
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I agree with the Bear. Coolant exiting first followed by engine oil is a classic example of the head not sealing due to warping, cracking, or a shot head gasket, or any combination of the above. Once you solve that issue, you should also check the mating surface of the block.
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Old 04-11-2020, 01:10 AM
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Bear, Rider, thank you.

Off we go...
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  #5  
Old 04-11-2020, 10:21 AM
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Don't know if you've done these before...if the crank and cam are zeroed on TDC compression stroke before disassembly and you fashion away to keep the injection pump/vacuum pump gear from moving, it will save a lot of work on the reassembly pump timing. There is a special tool to lock the pump in place.

Stuff rags in the timing chain cavity and remove the three small allen bolts in that cavity first.

Good luck!!!
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Old 04-12-2020, 08:07 PM
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Sugar Bear thanks for your thoughts.
I have not started disassembly yet, (waiting for factory manual), I have the manifolds off, gathering info and courage before I proceed on full head removal.
I do understand that the process of removing the chain from the cam gear and keeping tension on the chain is a delicate operation with no room for error.
I am at TDC at crank and cam. I still have my vacuum pump off of the block from prior work. Does the chain move a bit after it is taken off of the cam gear resulting in movement of the IP/vacuum pump gear? Or is the movement the result of slackening the chain tensioner, etc? (I am good at painting marks on parts for realignment at assembly.)
I will keep reading some of the great threads from a couple of years ago (where you pitched in) and keep getting my baseline knowledge up. (I have not had a head off of an OHC engine.)
Thanks again for your input, really appreciate it.
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Old 04-12-2020, 09:05 PM
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The chain can and likely will move along with the injection pump/vacuum gear. Time invested to prevent movement is a sound investment as is paint/matcmarking.

If the cost is reasonable, my instinct is to use a genuine MBZ head gasket, i.e., OE not just OEM.

Unbolting the head in reverse order of tightening sequence never hurts.

If your not planning on doing a valve job, have a machine shop vacuum test the valves and the head for straightness. Valve seals are easy when the head is off, a DIY.

Consider timing chain replacement too, I've seen a few break...sudden start to a bad day! If replacing the chain do it after everything is reassembled, then open the old chain, connect it to the new one, keep the old one taught and constantly in contact with the cam gear. Have an assistant turn the engine by hand until the new chain is pulled through, connect the two ends of the new chain...new chain and everything is still timed.

Meticulously keep everything in order so it returns to its original place. Take many pictures throughout the job.

If this was a gas engine there is a large hex head plug where the ignition distributor would go. Under that is a sector shaft that is through a bronze bushing inside an aluminum bullet shaped fixture, the shaft drives the oil pump. Check the bronze bushing for excessive wear allowing excess vertical movement of the sector shaft gear. I don't know if the aluminum piece with the bushing is still available if needed. If not a machinist could easily make the bushing.

Good luck!!!
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Old 04-12-2020, 09:15 PM
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The factory manual is the way to go; but, i gained a lot from a Haynes manual also on this job. It seemed to explain some tasks in a more DIY way.
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Old 04-12-2020, 11:19 PM
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Copy on all points, will do, thank you.

Appreciate the nudge on replacing timing chain, tensioner, etc. was thinking about it, good advice, likewise the MB OE gasket.

Keeping my fingers crossed that the problem was the head gasket and not anything beyond that...
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  #10  
Old 04-12-2020, 11:52 PM
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Disturb the head gasket as little as possible during the removal. It usually stays on the block but let it stay wherever it wants. Once the head is off, examination of the gasket frequently shows the source of the leak. Look for stains and/or corrosion that breach from a coolant passage to a cylinder or an oil passage. If you find a breach you found the problem.

Good luck!!!
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Old 04-13-2020, 03:51 AM
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Hi JSR some important points:

since your model is a '76 then it uses Hex bolts for the cylinder head and that means 3 things:

-You don't need new bolts because they are not stretch bolts.
-You will have to re-tighten your cylinder head after 300-600 miles.
-You engine can't use stretch bolts(according to the manual)

sources:
https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/615/05-105.pdf

https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/615/05-110.pdf


Sugar Bear already mentioned most of the important stuff.

You can check the stretch of your chain by pulling on it to see how tight it is on the sprocket or by the 2mm method in the manual:

also push on the tensioner rail to see how tight your tensioner is.


Because you have the vacuum pump off I recommend checking the end play of your timing device (Should be 0.05-0.12mm) If it's excessive then that can cause your vacuum pump to fail.
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Old 04-13-2020, 10:31 AM
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Quote:
Originally Posted by christuna View Post
Hi JSR some important points:

since your model is a '76 then it uses Hex bolts for the cylinder head and that means 3 things:

-You don't need new bolts because they are not stretch bolts.
-You will have to re-tighten your cylinder head after 300-600 miles.
-You engine can't use stretch bolts(according to the manual)

sources:
https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/615/05-105.pdf

https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/615/05-110.pdf


Sugar Bear already mentioned most of the important stuff.

You can check the stretch of your chain by pulling on it to see how tight it is on the sprocket or by the 2mm method in the manual:

also push on the tensioner rail to see how tight your tensioner is.


Because you have the vacuum pump off I recommend checking the end play of your timing device (Should be 0.05-0.12mm) If it's excessive then that can cause your vacuum pump to fail.



The info about the Allen bolts is very interesting.


Can they be substituted for the stretch bolts?
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  #13  
Old 04-13-2020, 10:43 AM
JSR JSR is offline
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Strelnik: From what I have seen, changing from one bolt type to another is an absolute no go.
Sugar Bear: Thank you, I will be cautious with the head gasket and study it, high hopes that I do see failure there and not elsewhere...
Christuna: Thank you, I appreciate the spec on timing device end play, will do. I am not able to pull/lift the chain off of the cam gear and cam gear notch and TDC mark on crank absolutely line up. I have nothing to compare it to, but will change tensioner as it needs to come off anyway and it is the original.
Thank you, all of you, for your replies!
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  #14  
Old 04-13-2020, 12:09 PM
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Quote:
Originally Posted by strelnik View Post
Can they be substituted for the stretch bolts?

bottom of page 3 and page 4 say that you cannot. The blocks that use stretch bolts have longer threads.


https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/615/05-105.pdf
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  #15  
Old 04-13-2020, 03:51 PM
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When you pull the head, double and triple check the head for cracks.

1980 240D CRACKED cylinder head + cavitation damage

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