: Exhaust leaks at Y-pipe to exhaust manifold and front ex. manifold to crossover pipe



KHE
06-02-10, 09:00 AM
I started up the engine on the '97 STS I've been working on last night. New head gaskets, bearings, seals, etc. It runs fine but there are exhaust leaks where the crossover pipe bolts to the front exhaust manifold and where the Y-pipe bolts to the crossover pipe and the rear exhaust manifold.

Everything was torqued to spec. I am going to recheck the fastener torque and if that does not solve the issue, I'll replace the graphite donut seals and see if that helps. I hope I can move the crossover pipe enough to change out the front seal... There is no seal where the Y-pipe connects to the rear head - it is just metal to metal which I thought was strange. I may use some exhaust cement at that location.

I've done this job before and not had this issue - it seems that EVERYTHING on this one is fighting me tooth and nail...

STSS
06-02-10, 10:18 AM
I didn't replace my exhaust gaskets when I had my engine out (even though it says you should) and I have the same issue (it's not REALLY loud, just louder than it should be when you get into the gas). On my STS (01), there was a gasket from the rear head to the Y... here is the page from advance that shows the two header to Y gaskets (#3 and #5 on that list)... the Y to flex gasket is a flat rectangular gasket with 4 holes in it.
http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/PartSearchCmd?storeId=10151&catalogId=10051&langId=-1&pageId=partTypeList&suggestion=&searchTerm=exhaust#storeId=10151&langId=-1&catalogId=10051&searchTerm=exhaust&pageId=ajaxPartList&category=&l1_categoryId=&l2_categoryId=&partType=&facetFields=mfrName_exact%2CpriceBucket%2Cclearanc e%2Csale%2C%2Cl2_category%2Cpart_type&beginIndex=0&filterValue=l1_category%3A%22Replacement+Parts%22% 7CReplacement+Parts&sortBy=4&pageSize=20&filters=l1_category%3AReplacement+Parts

KHE
06-06-10, 11:16 AM
It's fixed and does not leak. I decided to loosen the bolts on the flange and then run them in evenly so the clamp would remain even. I started the engine and the exhaust leak was gone.

The service manual made no mention of replacing the graphite donut seals. In the future, I would definitely replace them while the engine is out of the car.

None of the parts stores had a listing for the front seal so I bought one from the stealership for $16.00. It was exactly the same as the $8.00 Felpro rear seal.... Both new parts are sitting on the shelf for future use.