Timing Cover woes

[ALAN COCHRANE]

Hi Everyone.

My engine odyssey have now reached the point where the timing chain cover needs to come off. I have managed to remove six of the eight studs but the last two have resisted all my various attempts. The culprits are the inner left hand and outer right hand stud between the top of the timing cover and the cylinder head. Both now have damaged threads.
I've ordered a stud extractor set which will hopefully allow me to remove them.
Is it possible to lever the cover out from the bottom and then pull it down off the top studs?
Secondly can anyone tell me why studs were used in the first place. Surely UNC bolts would have been a much better idea?

Happy New Year

Alan

[abowie]

Is it possible to lever the cover out from the bottom and then pull it down off the top studs?

Secondly can anyone tell me why studs were used in the first place. Surely UNC bolts would have been a much better idea?

Probably not because there are 2 locating dowels and the front part of the central chain wheel spindle preventing this. It really only comes off forwards.

Jaguar did all sorts of seemingly dumb things. Studs are less likely to get stripped in aluminium perhaps.

Remind me what you are trying to do and whether the engine is in or out of the car?

[PeterCrespin]

Secondly can anyone tell me why studs were used in the first place. Surely UNC bolts would have been a much better idea?

Huh??? Why do you say that?

The use of studs results in less wear on the casting's threads - especially important with aluminium alloys (and even more with fragile magnesium 'race' alloys).

Using bolts in blind holes risks bottoming out and causing casting damage. This is exactly the timing cover scenario.

Tightening fine pitch threads is more repeatably accurate than coarse pitch threads.

Studs stretch on tightening whereas bolts stretch and twist.

Studs provide immediate component support and location, pending nut tightening. E.g. Clutch slave, pedal box studs, cam studs, inlet and exhaust manifolds, non-splined wheels

Studs are not always possible or ideal, but just because we can't figure something out doesn't mean Jaguar missed a trick!

[phil.dobson@mac.com]

For what its worth I have never understood how people can take the timing cover off without having removed the head. Whilst it is obviously possible (remove the studs etc) I can't visualise how you can put it back given the head is clamping the head gasket down onto the timing cover. Happy to be proven wrong , but if it were me I would that the head off. I doubt the stud extractor will fit in the location you are describing.
Just my view.
Happy new year to all.
Best regards
Phil D.

[ALAN COCHRANE]

Thanks for the replies.

The engine is out of the car so that the flywheel can have it's surface reground to remove spiral scratching.
I'm also taking the opportunity to change the leaking front oil seal, hence the timing cover issues. The cover can certainly be removed/replaced with the cylinder head in situ. A friend has just done it although he admitted it was a bit of a faff getting it back on with the gasket.
In answer to the bolt versus stud debate, there certainly doesn't appear to be any reason why they were used in the front of the sump. They certainly wouldn't bottom out since you can see the bottom of the stud through the casting. In addition Jaguar saw fit to use bolts in most of the front fixings so why not on all the of them?
I've already sourced the right length of UNC bolts for all eight fixings.
The stud extractor would certainly have enough space to grip the extreme right hand one but not the one under the crankcase breather. On this one I'm going to try an old trick I've used successfully before. Drill holes through each face of a nut and then tighten the nut onto the stud. The holes will act as a guide to drill though the stud and allow a small diameter drift to be inserted through both. A tap on the drift usually does the trick, especially here since there will be no rust issues. Otherwise it's cylinder head off time. Fingers crossed.

Happy New Year

Alan

PS Does anyone else smash all the Xmas lights at the top of the page every time they log in. A Trick cyclist would probably have a field day with this.

[chrisfell]

“PS Does anyone else smash all the Xmas lights at the top of the page every time they log in. A Trick cyclist would probably have a field day with this.“

Every time, every time.

[mgcjag]

Hi Alan...how about welding a nut to the stud.... Steve

[ALAN COCHRANE]

Hi Steve

I had thought about that option, but decided to use it as a last resort. SWMBO wanted to go for a New Year walk along the promenade and that's when I saw my opportunity. If I got ready first I would have at least a half hour window of garage time. I managed to successfully remove one of the studs using the technique I described in my earlier post. So hopefully I can remove the last one using the same method.

Cheers

Alan

[Hugo]

I've just re-built my engine, and in an attempt to forestall this problem in the future, I removed the offending studs top & bottom & replaced them all with UNC Allen bolts. In theory, if the timing cover ever has to come off again, I reckon I will just need to slacken the head & sump off a bit & it should pull straight forward.

[ALAN COCHRANE]

Good move Hugo. I've been told that you don't need to raise the cylinder head in order to remove and replace the timing cover. Here's hoping.
Well it's been a good day in the garage so far. After a bit of persuasion my specially adapted nut screwed onto what was left of the remaining stud. After drilling right through the stud and inserting the pin, it proceeded to unscrew as if there had never been a problem. Job done and time for a well earned cuppa.
As a result I've rewarded myself with a session on the blast cabinet. For some odd reason I always find this very therapeutic.
One of the items for blasting is the water pipe that goes between the back of the water pump and the bulkhead. Does anyone know if there's a stainless steel equivalent? I drew a blank on the SNGB website and none of the others seem to offer it either. I've toyed with the idea of using a 15mm chromed copper plumbing pipe but there is a stepped section at the bulkhead end.

Cheers

Alan

[abowie]

Does anyone know if there's a stainless steel equivalent?

We got some made up in SS a few years ago. With the car assembled you can't see the pipe anyway so copper is probably as good a choice as any.