Ok my series 3 ots is finally blowing so much smoke at startup that the neighbors are complaining. The engine runs great except for the first 5 minutes of smoke. My mechanic and I are in agreement that I need new valve seals but we disagree on how to do it. I have read several threads on this site and looked at a few YouTube videos that show the seals being replaced without removing the heads. It looks doable. My mechanic (who is an excellent, honest, jag expert) says that changing the seals with the heads on is so tedious and time consuming that for almost the same cost he could pull the engine, whip off the heads and do a proper valve job. I have got 65000 hard miles on this car and I know it will eventually need major surgery but I would like to try a bandaid. If I replace the seals myself the cost of parts is trivial. If I screw it up I’ll tow it to my mechanic who can say I told you so and pay for a valve job. So, I’m a fairly competent backyard mechanic. I know how to use a torque wrench and I have read the manual. I see two major risks. First, while the spring is disconnected, dropping the valve into the cylinder. Game over, call the tow truck. Second, i get everything back together but i failed to properly seat one of the valve spring retaining collets and when I start the engine the valve disconnects from the spring and drops into the running engine. Game over. Total disaster. Should I give it a try?
Dropping the valve is preventable. There are methods using compressed air, cord, rubber hose etc., youtube is your friend. Having the valve colletts come loose is only preventable by carefull work and confirming that they are properly seated. Your third option would be to do the work and 5hen pay your mechanic to inspect it before start up.
That’s a very good idea. I’ll have my mechanic inspect the Job after I have reinstalled the springs, before I reinstall the cams. Now about the rope vs. Compressed air to hold the valves in. If I use compressed air I wont have to turn the engine after removing the cams. My timing stays intact but if I push too hard in the valve stem to install the rubber seal I could accidently open the valve, the pressure would be lost and the valve could drop. Could this actually happen or am I over thinking it.
I would never try to take the heads off a V12 unless I absolutely had to. And you don’t.
I have done this on a Honda engine in the past using the compressed air method successfully. You use quite a lot of pressure (80 to 100 psi) to hold the valve, enough that it can turn the engine so make sure you have it in gear. As the pressure is all that is holding your valve it is vital that you keep an eye on the compressor gauge so that any leaks don’t let the pressure drop.
With the proper tool seating the collets should be doable. Coat them in a little grease before you reinsert them; this makes them easier to keep in place.
The stem seal will slide easily over the valve. It locks onto the valve guide so the chances of you pushing the valve into the cylinder are pretty much zero.
Agreed. I have inspected cross sectional engineering drawings of the engine but I have never seen one disassembled. If I take out the cam and use a magnet to pull out the tappet and shim will there be enough room for me to remove the spring and replace the seal? It looks pretty tight. Do I have to remove the tappet block? That would be a much bigger job.
I’m not sure; I’ve never done this on a V12. Others will have.
One thing I would consider is removing the bonnet to give you unfettered access to the engine. It’s not that difficult to do and otherwise I think doing the front cylinders would be quite uncomfortable.
EDIT. I rang Chris my boss who has built a lot of V12’s. He says that to get access to the springs to compress them that you will need to take off the tappet block. When reinstalled it needs to be sealed to the head with Hylomar. The critical issue will be getting a spring compressor that fits.
He says that removing heads on a car that is regularly driven is easier than if it has been stored for a while.
For sure, saving money at the repair shop only to give it to the chiropractor doesn’t make sense. I was planning to raise the front 6 inches, release the bonnet strut and tip it all the way forward. Should make the job more back friendly. Now, do I have to buy the jaguar cam sprocket retaining tool j40 or is there another way of holding the sprocket and timing chain after disconnecting the cam?
I agree. Its not that much work to remove the tappet block after having removed the cam. Besides, it will make fitting the valve stem seals and springs so much easier.
I’m with your mechanic. His IS an excellent recommendation and honest knowing that of course it will be more, but very worthwhile work. There is SO MUCH merit in pulling the engine, to clean, tidy and fix a 50 year old engine. The most important aspect for me is to also clean out the water passages with all the muck that is lying in the bottom of the coolant passages after 50 years of tap water in the cooling system.
My car is as perfect as they come EXCEPT, there must be a spot somewhere in the engine where such muck is lying causing a tiny hot spot , which causes coolant to be slowly pushed out the header tank on a hot day.
It can be done with the tappet block in place but you’ll need to make yourself a special tool. It’ll be like a pipe with the side walls on both sides removed, leaving a ring top and bottom supported by two thin pillars, about four cms tall. This goes between the spring compressor and the spring and leaves enough gap to manipulate the collets into place whilst the spring is compressed.
Good luck with the air method. You will need to turn the engine over to make sure both valves are shut on the cylinder you are working on.
I have a few sets of low profile Teflon seals in the loft for people with hot cams.
kind regards
Marek
Maybe I am over thinking this, but I think you may be on the edge of the slippery slope. IF you do decide to pull the engine, how far will you go? If you spend all that money and just replace the valve seals, will that solve your problem? Although it does sound like valve seals, maybe the oil rings are shot also. And while it is out, what about… resealing the engine, checking the bearings, throw out bearing, clutch, valves, guides, etc., etc., etc., etc. I have never done valve seals on a V12, but unless they are that much more difficult than most, I would either do them in the car, or if you pull the engine, at least be prepared to do everything now. FWIW.
Tom
The valves are going to be shut as there is no cam on the head 
but I agree that turning the engine over to get the volume in the cylinder down would be beneficial.
Thank you for all the expert advice. I’m going to give it a try. I started this morning by cleaning up my garage and work bench. Two hours spent putting away tools and the remnants of last year’s projects including rebuilding a trolling motor, fabricating a roller furler for my boat, replacing the mufflers on my motorcycle, rebuilding the swimming pool pump, and a dozen other project. Now I have a clear bench and a clear mind. This project will require my full attention. No fooling around. It’s going to take several weeks because I can only work on weekends. I’ll post as many photos as possible. I appreciate any and all help.
right now this car runs great. My last chance to back out. first, disconnect the battery. ok here is the first deviation from the factory repair manual. I do not have to remove the cross over fuel line, carb balance tube and PVC tubes. I just unbolted the intake manifold and it lifted right off. I’m keeping everything in order on the bench. I plan to clean and polish everything before reinstalling.
When you have the intake manifolds off, you have access to the inlet valve stems. Pull the valve cover and then the camshaft. Make sure you either put the engine at TDC for the cams or mark the cams so they can go back in the same position. There is a spring lever in front of the cam wheel to hold it when you remove it from the cam so it does not release the tensioner. Do not pull the tensioner to the lock position as per the shop manual as you will crack the tensioner. Using needle nose vise grips, clamp onto the valve stem and then using the factory tool, release the appropriate inlet collar and spring. Remove and install new seal and install spring and collar. Repeat for the others. Before you pull the cam, it would be a good idea to check valve clearances and there is no easier time to adjust them. No need to remove tappet block if you have the correct tools to remove the springs. Also, where you have access to the valve stem is not going to hurt to grab with vise grips as this area does not go in the guide.
I replaced seals using 110 psi air pressure to disassemble a VW Scirroco about 40 years ago. It was literally fouling plugs by bridging the plug gap. 500 mi/qt of oil. No warranty, “normal oil usage”, The “clean diesel guys” in their formative years. But I digress.
But there are 3 times more valves in a V-12 than my minor repair.
Accessibility and proper tools I would think is the key to being successful. That and a well thought out process. One mistake with a keeper would be pretty catastrophic. Plus - are you going to adjust the valves as long as you’re in there, right? So there’s more in and out of some of the valve gear.
All this says to me… testing. At least a compression test if not a leak down test which is preferable.
If seals are a bandaid for an engine with say worn, stuck or broken ring this makes no sense. Way more downside potential if not done correctly. Your mechanic may be speaking the truth.
Hard miles you say? Do the pro valve job, maybe re-ring the engine if the pistons are re-usable. Get a warranty/guaranty in writing. Do it once, do it right.
This from a guy who pulled his Jag head off 3 times. And I only had one head.
Both manifolds on the right side are off. Looking into the inlet you can easily access the valve stem and Dick’s idea of grabbing the valve with locking pliers is a good one ( I’ll probably use a curved vascular clamp with vinyl tubing covering the jaws) I could hold the valve and pressurize the cylinder. I like that idea. The valve for cylinder 1a 2a 3a 5a and 6a look dirty but relatively dry. 4a however is soaked with oil. The valve is closed and there maybe a tablespoon of oil on top of it. I think I found my problem. I took pictures but they don’t show well. I have a borescpoe and I’ll try to get a picture that way.
So now I’m thinking maybe I should only change the seal on that on guide. This would dramatically reduce my chances of causing damage. But first I have to get the cam covers off. There are three screws up against the inlet housing that I cannot possibly reach. Any thoughts.
Pretty sure I had to take the inlet housings off.
Cheers,
Lynn
Nope, I did not have to take off the inlet housing. I took off the air filter box and loosened the hose clamps on the short rubber hoses that attach the air housing to the engine. I then gently tipped the carbs away from the valve cover a wedged it with a door stop.
This gave another 1/4 inch clearance that let me remove 2 of the three bolts with a socket wrench but the third one was a bigger. I could reach it with a open end 3/8 wrench but my cheap wrench was too thick and coarsely made to fit around the head of the bolt without bumping the cover. so I turned on the bench grinder and thinned down the wrench head. and amazingly it worked! cam cover is off with carbs, carb housing and cross over pipes intact. You might almost think the engineers meant it to be this way.
Now I have checked the valve clearance. It is .011 on all valves except for one that is at .008. Is this the expected amount of wear for 65000 miles. Should I install thinner shims to bring the clearance back to spec? The engine runs fine. The valve train is quiet. Doesn’t the reduced clearance give extra lift like a performance can?
I probably would correct the 8 thou as you’re going to be in there anyway. But beware Shipwright’s disease.
Shipwrights disease?