I finished removing the cylinder head on my 1990 Xj40 today.

Preliminary I found my EGR inlet into manifold was plugged with grease and water. Probably the source of my elusive chk engine light code. I also found my air pump pipe to exhaust had been corroded open on the intake side just before the flare nut. The compression fitting going into the rear manifold from that pipe could not be removed from the manifold.

- Lessions learned: Clean the throttle body regularly and don't spray seafoam in though the throttle body on these cars. The egr inlet is directly under and past the throttle body and is a prime place to collect anything that might run in there.

Removal of the head revealed a clean engine however it had white build up on the exhaust valves. I presume from lean running condition. I also found a burned valve on the number 4 cyl. (not the num 5 like I had thought). Asside from the oil weepage from the usual places the gasket seemed intact with minor leakage between the 5 and 6 cyls.

- Don't neglect lean conditions, I am presuming my lean running was caused by the ECU running default values as a result of faulty egr as well as another underlying problem. Find these problems and fix them before you are replacing valves!

The real horror I had found was the corrosion of the water passages. There was deposits of what appeared to be calcium throught and a few of the water passages were completely plugged at the gasket--explaining the overheating issue in summer months. The engine block had some minor corrosion around a couple of the passages which was alarming but not a real concern for me. What I found scary was the amount of corrosion on the head. On two cyl. the corrosion had eched up to 1 mm or more deep up to the steel ring on the gasket that encloses the cylinders. Way to close for comfort.

- Always use approved antifreeze with the proper corrosion inhibitors. Always use distilled water when mixing. Otherwise an acidic or basic water along with calcium and other minerals can destroy these aluminum engines.

Pictures to come tomorrow but from what I have learned: If you have a Jag with over 100k miles on it and you are not sure what the last owner did to it (even for 50k of those miles) and you have odd or unexplainable issues it is probably a good time to tear it all down and see what is going on.

I know my cars previous owner filled the radiator with tap water. I also know that due to my personal neglect at getting to the root of a seemingly harmless EGR problem has caused me a burned valve.

 

Tap water is a bad idea that can clog water ways and this could cause engine overheating and hence big repair bill

I didn't know EGR Valve to take its toll and wreak havoc more than I expected .Burned valve sounds terrible

 

Photos as promised:

Head Front.


Head Back.


Corrosion around #3.



Corrosion around #1



Burned Valve, the seat is ok.


The valves are a major pita to remove. They are stuck in there good with the clips. I have the most jerry rigged contraption to get a standard spring compressor to work. I won't post photos of that but I will say it involves rope.

 

Great job gunner! Thanks for the pictures.

 

Well she is about ready to go back together. New exhaust valve fitted and new seals on the intake side. The exhaust side was not done because I forgot I had enough seals for that side and it is harder to get those out.

As you will see the larger corrosion spots were filled...with you guessed it JB Weld. A welding and machining would have obviously been the better choice but this is a budget job where time is of the essence. I am also curious to see if it works. It is not in any very critical spots and will only contact coolant if anything.

The area was cleaned,brushed, and sanded untill clean. Using a toothpick I slowly filled in the pitting untill I had filled up the area. Saran wrap was placed over it to set. I then sanded by hand on the epoxy with 220 grit until it was nearly even with the head. After that I lapped an aluminum 3 x 3 block I had flat and used it as a sanding block with some 2000 grit wet sand paper to bring it down flat with the head.





The end result was very satisfying and I am feeling good about it. Almost all cleaned up and ready for install.


Getting the head off the car is fairly easy. Servicing the valves and head took me many many more hours. Will update on the success (or failure) of this project tomorrow.

 

Well the reassembly was a failure.

No start, she hardly tries. She will give a sputter if it has been sitting for a while. It had that easy sound of the starter cranking on no compression. So I checked Number 1 and behold zero compression on the dial.

I suspect a timing issue and/or a valve clearance issue. The exhaust valves that were not taken out all had stock clearance. However the intake valves were all removed and let sit overnight. I think between cleaning the seats well, letting the springs relax for a day, and flipping the shimms made them tighter because they were a few marks under the minimum allowed clearance. One of my headbolts was to tight on accound of a broken torque wrench when it was fixed as well as the cam shaft bearings loosened slightly it restored some of the clearance.

Also, even though there is no chain slack and the cam shafts line up with the marks I made I saw that the intake mark was slightly off (by a rats hair) but the marks also are not pointing straight up like the exhaust is (and the manual says).

This weekend I am going to double over and make sure my crankshaft is in right time with the cams, ensure valve clearance is within spec, and rotate the cam slightly.

The compression needle did not even tick during cranking so valves must be leaking.

 

Did you perhaps install 180 degrees out of phase?

2 rotations of the crank = 1 rotation of the cams

 

I don't think so but plan on double checking tonight. Last I recall the dizzy rotor was set to fire the number one plug as the #1 piston was at tdc. Both cam shaft lobes were pointing up and in at eachother and my marks ligned up.

I think my issue is my intake timing is off by a smidge. The cam shaft when taken appart was a bit off from where it should be (the notch facing perfectly perpendicular to the head) and the cam shaft being just a hair more off during reinstall, along with 100k mi of any sort of chain slack tightened up, might just be pushing it over the edge.

Tonight I will double over everything and try to readjust the cam. Are there any tricks to turning the cam shaft without removal of the journal caps? It only needs to go maybe a few mm. I was thinking if I could get a cloth pipe wrench around it it would turn but then again it would still put a localised force on a couple of the teeth.

 

Double check that the cams are corect (intake on intake side and exhauston exhaust side),also that they are timed spot on (the timing tool makes this quite easy).If you are handy you should be able to make one.You also said that its been sitting for a while,disconnnect the fuel line and pump some gas out of it (ther might be some water in there).

 

I went home and eyeballed the cam shafts to be at a more proper possition to see if it would improve anything. The car now at least fires a bit and even ran for a second with the dizzy severely advanced. I tried to do a compression test but my loaner tester turned out to be broken but it now sounds and feels like it has a lot more compression than it did.

I was going to make the tool but I figured by the time I went out and found some steel to work with and took the time to cut it well it was more appealing to just order the tool. So it should be here by Sat. I have my fingers crossed, I am starting to feel like a kid who got an Xbox for Xmas and the TV broke after I pluged it in.

 

Well thought I would update one last time as I hate seeing threads that have no outcome after so long.

I finally got the car running today. The cam algnment tool appeared to be a waste of money this time. My eyeball was about as dead on as you could get, the tool only made for miniscule and I mean small change. Do it all again I would have the tool in my drawer at the start of the job though.

After week one when I readjused the cams 'by eye' it would try to fire. I chaulked it up to bad cam timing and got the tool.

Tonight after ensuring cam timing I reset the dizzy position to just be in line with the notch, cleared the ecu, repaired a small corroded brown wire coming from the battery, and tried to start. It would start to run with wide open throttle and after a few tries she finally took off. The problem appeared to be something to do with the ecu and the distributor possition. The only thing that seemed to stop it from running tonight was a flooded condition.

Otherwise seems to be a job well done. A run around the block and she is running better than ever before. All in all I am not sure what the problem was except that it seemed to want 3 weeks off from driving.