List, I am fairly sure that my 1984 blew the head gasket. By cranking, I pressurize the coolant system, and there is a small amount of oil in the expansion tank. It doesn’t start or run well either.
I‘m now looking for the best gasket for an early injected 4.2 (I plan to take Martin Scherz’ gasket and get him the best available in return).
It has the slots between the cylinders. Are the composite gaskets with the rubber and the steel rings good? Is the chance that no machining has to be done in my favor?
I plan to leave the head stud ‚fix‘ in place and will do the same to the stud that I assume to be broken. I have absolutely no interest to spend weeks on a proper repair.
Besides the gasket, and having a look at the bores and valves, anything else that I might want to look at while it’s open?
If your goal is to slam’n jam it, you must check head and block flatness, preferably with a machinist’s bar. A new head gasket on either a warped block or head ain’t gunna last long. In the eventuality both are reasonably flat, the composite gasket is your best choice.
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Traditionally, David; a ‘valve job’ is done while the head is out. Ie, lapping in the valves - checking them in the process…
You should also run a compression test before removing the head - and I assume you are loosing coolant…?
And if you have a broken stud; it is quite likely the cause of the busted head gasket - and the new one may then fail quickly. Head off is a rather extensive operation and any work done with the head off sometimes add little time and cost to the gasket change…
Will do! Was thinking anything about the chains especially.
Frank, I know I would need to check and remove the springs for lapping the valves, and I don’t have much time for that. I want to be back on the road soon. A compression test last year (I think, time flies) yielded good results.
I will not slam the gasket on with a stud missing; but I won’t be drilling and cutting out the two old studs on a tired motor either. I’d rather repeat the cheap repair that seems to hold up well, which is basically imitating a short-stud block with third-world methods. Please understand that I don’t like the idea much either.
If I was to keep the Jag for another ten years, by then I might have a proper place to properly go over everything without tens of people walking by or such.
I will update on the progress.
David
Three studs broke, so I took @MartinScherz ‘ leftover long studs, cut a M10 thread on them, used inserts into the block face with M14 or 12 outer and M10 inner threading and put it all together this second time. Judging how hard the inserts were to screw in, this will never come apart again. I figured given the state of the block it doesn’t hurt anymore. While at it I manufactured a new microswitch for the throttle.
I‘m not proud of the repair (but I like ghetto jobs) and when I sell it I‘ll mention that in case of breakdown a new block won’t hurt. I was a bit shy of torquing as there still are corroded studs I can’t observe, but it holds up well. The three shiny ones are mine, the two others were there already, and they didn’t fail that soon even though the slotting and all…
Pistons are oversize but look good. The rest was criminal. Parts missing, cam timing off and so on.
I did clean off the pistons as well as I could, but, well, whatever. The crumbs will burn off, no tricks that I know of.
We almost forgot the gasket when we lifted the head back on! Else - fine!
Great job, David! Looks like you made the very best out of a less than ideal situation. If you feel like keeping the car you may look for a decent engine or save money for a full rebuilt.
Looking at your findings it is inspiring how well the engine ran prior to the rebuild …
The reason for the ‘long’ stud arrangement is to take the stress of the head to the bottom of the block. Relieving tension on the slim sides of the block - cast iron is not very strong under tension. Don’t go racing with your engine set-up…
I won’t go racing anymore. On the other hand, two studs have been repaired this way already and full throttle has never caused a problem over thousands of miles. I’m more worried about the tension on the block deck which is an issue the short stud engines had, too. Apart from the threads only having about half an inch of cast iron.
I’m more worried that it started up in the wrong direction yesterday - twice. It had run very well a dozen times and I didn’t change anything so how do I like that! I’ll try to figure that one out for myself first. Few people appear to have seen that sight. May start at looking at the timing (cannot see what should have changed) and go from there.
Jochen, I found a picture of how I bought it. My main goal was to move it out of that garage under its own power which did happen. Now it’ll have to happen again which will also happen
It was maybe a full cycle. I‘m thinking residual fuel, kickback of sorts and then running (on way retarded spark) until it was too lean or I cut the ignition. Very interesting. I wonder why today and never before.
When I bought it spark was way advanced, often kicked back but never ran. I‘ll find out why.
It is not cam timing, that is set and ran well. The last thing I would check, but I can do that. Everything is tight. I can’t imagine excessive buildup but I‘ll check (that will have to be next week or so). I also didn’t move timing but set it statically again.
I‘ve found a few videos of engines that run backwards. Notably a v8 on a racetrack that is clutched in reversed during a spin and starts idling strangely, sustaining itself. And a few claims that people managed to do similar things. I assume such engines are generally fine and mine just somehow moved backwards after releasing the starter and found something to ignite. I‘m simply not sure yet as to why.
David you should rightly be proud of the accomplished! Not that many young men around to tell the tale of fixing their own xk engine, let alone working out the problems. Here one of the old studs David traded in for one of my good used ones:
