1985 635 CSI Timing chain.

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SixerNick
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Joined: Fri Apr 17, 2020 4:21 pm
Location: Eugene Oregon

1985 635 CSI Timing chain.

Post by SixerNick »

Good morning. I have a 1985 635 CSI. The car has a leaking at the timing cover. With that I was thinking of going ahead and having the timing chain replaced at the same time. The car has 257,000 miles and runs really well. What other things should I have done while I have this done? Thanks.
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Ralph in Socal
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Re: 1985 635 CSI Timing chain.

Post by Ralph in Socal »

Since your goal is to fix a leak you're likely removing both the upper and lower covers

This is a pandoras box you can open. The oil pan gasket and Head gasket are both affected by the front covers. Oil pan overlaps the lower cover so Gasket damage is likely. Actually an easy decision here to replace the pan gasket also

Head Gasket is sandwiched between upper and lower covers. HG also prevents removal of the plastic chain guide which should be replaced. I've heard of various solutions to cutting a section of HG but would not recommend anything other than replacing the HG also. At this point do you have the head redone? The rabbit hole gets deeper and deeper. I have a couple of recommendations when you decide to do it

Ralph
Last edited by Ralph in Socal on Sun Sep 11, 2022 12:16 am, edited 1 time in total.
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81 633 csi (retired)
SixerNick
Posts: 22
Joined: Fri Apr 17, 2020 4:21 pm
Location: Eugene Oregon

Re: 1985 635 CSI Timing chain.

Post by SixerNick »

Thank you. I was basically told that the oil an was leaking as well. Actually all of the leaks are more is a speak as it does not leave spots at this point. The shop just wanted to do the pan and the timing cover seals. It was my idea to do the chain as well. Sounds like I may want to do everything at this point. Head gasket included? Hate to have to tear it down that far, just want it done right. I would tackle this myself if I was not working 70 hours plus a week. Just trying to make this a nice car to drive anywhere I want on rate time off.
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RossDinan6
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Location: SW FL, USA

Re: 1985 635 CSI Timing chain.

Post by RossDinan6 »

Ahhh, the old "while I'm in there". Nothing to add here, but been there done that.

I tend to do anything affected or found when removing bolts. So far this has not caused a major engine overhaul. It has caused much project creep.

Good luck.
Ross
'84 633 Dinan turbo
Jackie&Gracie
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Joined: Fri Nov 11, 2022 7:51 pm
Location: York, PA

Re: 1985 635 CSI Timing chain.

Post by Jackie&Gracie »

My experience with this engine is limited, but if and when you come across gaskets with some age it is smart to replace them. You have, by that point already paid the mechanic to tear things down, the best thing is to replace the gasket.

If you don’t then the picture is - he tore it down, did other work, put it back together and it still leaks. Now the answer is pay to do it again just for the gasket.

In this case, since part of the work involves opening the timing cover seal that connects with the oil pan (correct?) I would be tempted to do the oil pan gasket too.

So in one shot - cam cover gasket, timing chain gasket, oil pan gasket. Add to that any plastic involving timing chain tensioner. With the oil pan off this provides the opportunity to look through the bottom of the pan - kind of a “health” check on other things. That done, there should be few, if any leaks at all under the engine.
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