M20-Time for a Rebuild (or not)?

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M20-Time for a Rebuild (or not)?

Post by EBSF » Sat Aug 30, 2014 2:33 am

I have a very slow coolant leak on a M20 with about 150K miles on it, and am about to get it pressure-tested. It's either a hose or the head gasket. I'm thinking it could be the HG because (a) the oil seems a little lighter in color; (b) I had a brief overheating episode a while back when the auxiliary fan fuse blew on a hot day in stop-and-go traffic on a freeway, with the A/C on; and (c) I can't seem to locate any other leaks.

If it turns out to be the HG, the question is this: If I'm going to do that job, does it make sense to rebuild the bottom end at the same time, given the mileage. Secondary question: What about replacing other seals like the oil pan gasket. The camshaft seal of course, but anything else?

I'd do an S52 conversion but this is California and I have no appetite for the brain damage to get that past smog.

Also, I'd do it myself but don't have the time, so this is a cost-benefit question more than anything.

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Re: M20-Time for a Rebuild (or not)?

Post by Yoshi » Sat Aug 30, 2014 2:37 pm

If it was a head gasket, you'd likely have overheating issues. Buut I guess I've seen it happen like this before.

If it winds up being the head gasket, I'd just do the head stuff. It's tons more work to take the bottom end out. Course, if you're there, might as well redo the whole motor and have it factory fresh.
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Re: M20-Time for a Rebuild (or not)?

Post by M20_fever » Sat Aug 30, 2014 6:36 pm

if its just the head gasket then just fix the head gasket. When I pulled my donor engine apart at 215k miles there was still crosshatching on the cylinder walls and the bearings looked fine, m20s are like twinkies, they last forever. I would do the cam seal with the timing belt, water pump, and tensioner obviously.
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