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I have a newly acquired 1985 jaguar with a fuel injected double overhead cam inline 6 cylinder xj6 model . It has either a bent or stuck exhaust valve and runs real crappy . I’m a little intimidated by pulling the head on this car to fix it . Does anyone know anything about these motors that could help me through this process ? If it ends up being too much for me I’ll have to sell and move on . Thanks
So a little back story this car used to owned by my employer and I would bring it in for service. One day driving back from getting an oil change I noticed it running a bit rough and starting to skip. When I got back with the car it was running shitty and I noticed a long chunk of yellowish fiberglass hanging out the tailpipe .we took it back to the garage for a new exhaust system because it turned out the packing in the muffler had came loose due to a rotted muffler. According to the mechanic this clogged exhaust had caused excessive back pressure bending an exhaust valve . They did pull the valve cover and stated they could not free the valve and we should take it to someone more qualified to work on these engines. So the car came back to our garage and sat there a few years until I made them an as is offer. I’m having buyers remorse now because I think I bit off more than I could chew .
drop the exhaust and see how it runs.
Back in the 80's we had a benz in the shop that would start and then immediately shut off, troubleshot for days everything from the ignition to the fuel injection.
Finally, we dropped the exhaust it fired right up and was fine. The exhaust was so clogged it caused the car to stall.
Long shot but it's a lot easier than removing the head.
To ID a damaged valve train component do a cylinder leak down test. I've never heard of muffler packing coming loose like that and clogging the exhaust. If it can happen then it would surely be on an English car though.
To ID a damaged valve train component do a cylinder leak down test. I've never heard of muffler packing coming loose like that and clogging the exhaust. If it can happen then it would surely be on an English car though.
^^^^ This is what I’ll do first when I get it home and go from there . Thank you all
I actually was just looking at this site. You guys have me half talked into a small block swap. If I wasn’t such a die hard olds guy I might try it.problem I’m having is this car only has 28,000 miles on it. If I can’t fix it relatively cheap then I’m going to pass it on to someone more qualified. The way car prices are going I should at least get my money back.
The SBC swap was so popular several years ago it would be easy to do. They had all the stuff to make it look like it came in the car. That is a really low mile car.
Double up on this but I believe the XJ6 inline 6 has a GM turbo 400 transmission tied to it and also a GM Frigidaire AC compressor. Back in the day I had a 1986 V-12 XJS and had those GM components making the swap a bit easier.
Find someone that is competent and knows those engines. Don't expect it to be cheap. but, again, you haven't determined the problem. That car is very nice, and 28,000 miles makes it desirable. If you decide to "bastardize" it by installing and off brand "belly button engine", your market value will drop like a rock and the pool of buyers will get a whole lot smaller.
The inline six engine has been around for decades and was reliable. It wasn't a high revving Gran Prix type engine and not the most powerful.
Don't worry about dropping the value of your car. It's a 4 door and an I6, not a V12 or XKSS. Just keep it on the road, even if that means putting a SBC in it.
It all really depends on what somebody wants to do with the car. If they want to make a driver out of it, I would go with the SBC. If they just want it to drive occasionally and take to car shows, keep it like it is. If they want to flip it, get it fixed and sell it. A SBC is hardly an off brand engine. There are more of them out there than any other engine. Where is the rule that says if you love Olds engines (which I do) that you have to hate SBC's (which I don't).
After messing around a bit here’s what I come with . Since the car runs I started out by pulling one plug wire at a time and found #3 was the culprit. I did a compression test on all 6 cylinders and get between 118 and 120 on every cylinder except #3 that one has 0 compression . I then put 100 lbs of shop air to the #3 cylinder while it was at tdc and the air flows directly out the exhaust pipe .using my bore scope in the #3 hole I can see what looks like a witness mark where the valve possibly made contact with the piston but doesn’t look all that bad.my next step will be to pull the valve cover and check for a broken spring and try to figure out why the valve struck the piston.To me it’s hard to believe a clogged muffler could cause this.”to be continued”
Well here we are in september and the car is still sitting. it doesn't look like im going to do much with this car so ill offer it up for sale .Should i list it here in the non oldsmobile parts section ? i don't see a non oldsmobile cars for sale section .
April 19th, 2023, 12:49 PM
