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Yes ~ It looks pretty good. Those minor rust marks are nothing. Sand off. Decarbonise & measure bores & check for taper & ovality. Run on good gasoline in future with a decent additive system. Clean valve tulips. They are likely fouled. (inlet)
Last edited by Glyn M Ruck; Jul 23, 2020 at 10:15 PM.
I cleaned the top of one piston #6 so I can see the markings. I used my dial bore gauge to measure cylinders 2-5. They were all uniformly over by .010" top, bottom, Longitudinally and widthwise. As for the valves, I took a shot of #5 exhaust valve seat and can see carbon deposits (spots). So I'm thinking that the carbon on the valves is the cause of my low compression readings.
Any depositing on the back of the tulip of the valve will be a combo of poor gas & Multigrade oil coming down the valve guides & the polymer VI Improver burning onto the valves.
Decent additised gas like Techron will keep all that clean.
These early engines had no valve guide seals which I'm sure contributed to much of the crud buildup. So even though they may not be worn I'm going to replace all of the valve guides with ones that can use seals.
I finally got the engine off of the pallet and onto an engine stand. I removed the oil pan and timing cover. The chain tensioner is extended, so it is probably stretched. The oil looks a bit burnt so I sent a sample out to Blackstone labs for analysis. Good news is there was no sign of any metal after I dragged a magnet thru the sludge at the bottom of the pan.
All that crap and sludge in the engine is probably from too may short runs and people who think it's good idea to let the car warm up in the drive way for 20 minutes or more before driving.
They may polish out. I assume you're going to do a full overhaul, in which case the crankshaft needs to come out, the sludge traps removing and the traps clearing out, Why these were put in nobody knows, as clogging of them is one of the downsides of the XK engine. The screw-in plugs are secured by punching at the edges. I had all mine removed and I then cleaned them out plus the passages. Don't use any pipe cleaners, just wire and kerosene. Obviously you will be replacing the shell bearings. It would be possible with the crankshaft out to install the lip-type seal kit that replaces the rope seal. This involves grinding the crank to remove the spiral. Alternatively, you can replace the rope seal, but it is a PITA to do. Too loose and oil gushes out, too tight and the friction heats up the rear of the crank, melts the rear main bearing and......end of engine !! I managed to do the seal on a 4.2 XK out of my 1980 XJ saloon, but I still got some oil weepage, it is considered normal amongst XK aficionados !
Whilst I have never fitted one of these kits , I only know about them, I was intrigued to find with a little searching that there are several around, and one has to choose the one most suited to the engine and transmission: -
The kits that fit where the old seal goes allow either manual or automatic gearboxes to be fitted and involve machining of the crank to remove the spiral.
That crank needs to be checked for straightness, and out of round.
You can see where it's gotten hot and scored, there is a good chance it will need regrinding.
The scoring looks deep enough where polishing will not take it out.
Given the condition of the crank, have the rods and wrist pins checked as well.
I think what you are finding here is that a painted and highly polished engine can still hide some wear and tear inside. I once bought a Ford Xflow engine with a lovely new coat of blue paint and was told it had all sorts done to it. New pistons, Duplex chain, ported head etc etc all internal components..... When I eventually stripped it down six months later to check it before the installation I found it to be a standard 1300 with nothing done to it and the seller from up country no longer contactable.
Bearings are shot. Mic the crank & likely grind. Take Fraser's oil gallery cleaning advice. Oil sample analysis should show if that oil has been in the engine for the previous service period. Not if it was recently changed.
Oh yes, this is a total rebuild. I knew it was an old engine. The crank would need to have work on it for the rear oil seal anyway. I'm taking my time, enjoying the process. I work cheap.
It's all a bit meaningless because you don't know how many miles/Km's the engine ran for on that oil. Viscosity is low suggesting some fuel dilution or very bad shear of VI Improver from cheap multigrade oil, or both. Some of that copper & lead comes from the bearings.
Rebuild. Fill with new known oil. Run-in & drain at 1000 miles on no better than an SF mineral oil. Then put in a decent synthetic meeting Benz 229.5 and sample after 5000 miles.
Don't try to run-in with a top synthetic. It will take forever to break-in & could leave you with an oil burner. Protects too well.
During run in watch the temp gauge. If it does not rise alarmingly you know you don't have a tight engine. Do the first few 100 miles driving normally at below 3000RPM. After that raise Rev levels with short bursts at full throttle with frequent back off to draw oil up into the ringbelt. Watch temperature. If it rises badly back off.
Don't adhere to Jags old run-in recommendations or you will retard run-in with modern oils & risk an engine that uses oil.
Last edited by Glyn M Ruck; Aug 22, 2020 at 05:52 PM.
While the head is out at the machine shop I've turned my attention to the carbs. I broke the bolt on the center float bowl that was connected to the starting carb so I sent the broken one as well as a good one to Joe Curto. I just got them back along with a custom rebuild kit Joe put together. He drilled and tapped the plain float bowl and replaced the broken bolt. The broken one he just drilled and tapped a plug so it wont leak.
Instead of the old cork butterfly shaft seals He sent some flared rubber seals but no dust seals. He told me these did not come with them, so I have to reuse the original tin cups. I coated the seals and shafts with a light coating of white silicone grease. I didn't remove the throttle stops in the process.
