1997 SOHC oil leak

[Neil1750825]

Hey guys. Sorry if this is in the wrong spot. I recently replaced a 97 SOHC engine about two months ago with another junker motor. The original one lost a head gasket and had bad timing chains. I got it from some shady guy called Park Motors in Michigan and he screwed me over on the price and all and the condition and that another story for another day. The question I have now is I have the engine in and running pretty well. I just have a vibration at almost exactly 2500rpm in every gear. Also, there is an oil leak somewhere in the back of the engine. its been that way since i installed the engine. The oil drips off the seam of the bell housing and engine mating surfaces and onto one of the cats where it either pools on the ground or burns off depending on the temp. I put two quarts of oil in it over the course of probably 3 weeks so the leak is pretty bad. Its worse when i drive it hard. I assume its either valve cover gaskets because i opened them up to look at the timing chain guides and didn't use new when i installed the engine. otherwise it must be a rear seal? could use some input. Thanks in advance, Neil

 

[2000StreetRod]

possible sources

Many members replace the rear main seal when the engine or transmission is pulled. There are a few other possible sources of oil leak. The rear/right hydraulic/spring timing chain tensioner, the right cassette lower positioning bolt, the jackshaft rear sprocket cover/plug, the seal between the block and the block girdle (upper oil pan), the lower oil pan gasket or the valve cover gaskets. Check to see if the valve cover bolts are tight (71 to 88 in-lbs). Use a mirror or camera to try to see the area between the rear of the engine and the firewall.

 

[Neil1750825]

Update

So I have the engine nearly pulled after only two nights of wrenching by myself. Upon further inspection, there is oil all over the back of the engine. The bell housing is covered and I really though the rear main was the problem but I pulled the starter and found no oil inside. so its probably not the rear seal. it almost looks like its coming from he head gasket but I don't think it would run as good as it does. just got 17.5 mpg last weekend when I drove it 300 some miles. If it was the head gasket I think I would have noticed the lost compression. Going to have to check the locations you mentioned here. Can't post pics though I don't think. Also, the whole bottom of the engine is covered as well. all the way up to the oil pressure sensor. BUT, that being said, I lost a power steering pump a few months back too when I swapped the engines so quite frankly EVERYTHING is oily under there. Any help would be appreciated. Thanks.

 

[Neil1750825]

Update 2

The valley is full of oil. Not sure how it could be getting in there. Any suggestions. Toward the rear of the valley there is maybe a half inch of oil pooled in there. It is running down around the bell housing starting where the thermostat housing would bolt to the head on the BACK of the engine. There is a plug that covers where it is but basically anyone who knows the engine well should know what I'm talking about. I'm thinking about replacing basically all the gaskets and going from there. Any input would be appreciated as this job goes on daily. Thanks for quick responses and any help is help.

Neil

 

[BubbaFL]

If the valley is full of oil, it's very likely coming from the left cam chain tensioner.

If the crush washer is missing or damaged, it'll leak, fill up the valley, and run down the back of the engine.

 

[Neil1750825]

BubbaFL, you were 100% right. Its just a shame you posted about two days too late. I ripped the engine out and as it was hanging from the hoist in my shop, I figured I would degrease it and clean it so I could crank it over by hand and try to build enough oil pressure to find a leak. So as I was vacuuming an oil drenched mouse nest out of the V, I saw a glint of copper. It was a copper ring that could almost fit over my thumb and about the thickness of a piece of .05mm lead. I set it aside and finished cleaning the engine. I hooked a good cordless drill to the harmonic balancer and pulled all the plugs and started cranking. The oil was drooling out right where Bubba said. It was leaking pretty quickly down from the cam chain tensioner on the Driver's side head. Apparently some less than honest mechanic dropped that copper crush washer and didn't install it on the cam chain tensioner. It may have lasted 10 years or 10 months because I don't know the history of the engine but it did fail on me. Could have been 4 or 5 hour job if I knew exactly where I was going but since I had to yank the engine to get a full perspective on the situation it ended up taking 30 or so hours by myself. Props to BubbaFL though for the heads up. Better late then never. Hope it helps someone on the way. I have pictures but I don't know how to upload them. Thanks again.

NEil