Jupiter restorations.

[David Morris]

Hi David,

Sorry you are having problems with the engine. No, I don't think the problem is with the distributor. I have used distributors designed for an early MGB, with no problems at all. It was just that you can get new ones really reasonably and the engine ran well with them! The drive dog just slotted into the end of the Jowett drive shaft perfectively.

Have you just rebuilt the engine? And if you have, did it rotate easily after rebuild? I have encountered a problem when using Series 3 con rods in an early block. At least one of the big end bearing caps fouls the inside of the crankcase, not by a lot, but sufficient to lock rotation. The solution was to 'ease' the offending part of the casting.

Other than that, it could be the clutch. There isn't much clearance for the clutch bolts inside the bell housing. Will the engine 'rock' slightly backwards and forwards? If so, I would suspect at least one of the clutch bolts is proud. Is the starter motor free? It could be that the bendix is jammed into mesh with the ring gear? It might even be that the valve gear is preventing engine rotation? A stuck valve perhaps? If you lift off the rocker shafts, you can 'ding' the valves with a light mallet to see if the are free.

Others will hopefully suggest more ideas, but I hope you soon find what is the cause. Just don't force it to rotate, it's trying to tell you something!

All the best,

David

[Srenner]

All the above could be the problem. Sight unseen and stabbing in the dark, I vote for stuck starter motor. Lucas put a square on the end of the shaft just so one could release the bendix from the flywheel.

So just like my mom would say, when was the last time you turned the motor?

Going back to the build process, did you turn the rotating parts during the build? Likely you had to when fitting the con rods, turning the motor to get the rod to miss the crank throws.

Setting the cam timing. Did you do full, correct direction rotations when checking this?

And so on.

Good luck.

[Keith Clements]

As David asks, did engine rotate after rebuild?
Reading between the lines of your post where you were inspecting bores and perhaps looking for rust or scouring but still saw honing, you did not rebuild and you never saw the engine turn.
We can make suggestions once this is confirmed as there are so many possibilities.
But other questions does it rotate backwards at all? Seized means it does not move either way.

[David Kemp]

I fully rebuilt the engine & had it running sweetly.
I left it for months after that as i wanted to complete the fuel system. It was then i found it seized.
Since last post, i have drained the oil & found water in the oil.
I put compressed air down the plug holes & the engine turned.
It will now turn 300 degrees. I am pucking up a leak down kit tonight so should know more tonight.

[Forumadmin]

Did you use original con rod bolts? New ones can foul on the liners and possibly end float might have brought them into fouling.
Most likely is a stuck valve or cam follower but that should be obvious on the tappets.
Possibly debris in oil pump but if crank locks consistently at same point of 300deg then probably not.

Water in oil is probably head gasket but might be crack in head or block or seal on liner. Endoscope might show rust on one cylinder or rocker cover may have water drops in one bank. The latter is often seals around head studs the rubber centre or solder on other studs.

[David Morris]

Hi David,

I hope the leak down tester gives you some further clues. You say the engine now turns through 300 degrees, so I guess it is still not going through a full revolution? Does it just get tight, or completely refuses to go through 360 degrees? My best guess would be a stuck valve?

Water in the oil is never a good sign. I think it might be posible, with a bit of inginuity, to arrange a form of air pressure testing of the block, once you have drained the water? You would need to block off all but one of the water inputs/outputs and see if the block holds air pressure. What is the engine number? We have found the Series 3 engines to be the worst for cracking, as the castings seem to be thinner. The earlier ones were much heavier and stronger. There is a theory that the magnesium in the alloy tends to lead to intermolucular corrosion, limiting the strength of the later castings.

I know from bitter experience that, having rebuilt an engine, and then to encounter problems is disheartening, but I am sure you will find the cause. There is always, as a last resort, K Seal ( professional grade ). I believe, on good auhority that this sealant was so named for it's use on the Rover K series engines, that were always suffering from head gasket water leakage problems!

All the best, and good hunting,

David

[David Kemp]

Leak down test shows leaks every where.
1 cylinder is leaking out the exhaust so stuck valve seems likely. I will tear the engine down on the week end.
It is dusheartening , but to me a learning experience.
By the time I sort this car out I will be an expert or insane.

[Keith Clements]

I would not rely too much on leakdown test on such a new engine as bores and seats might not be bedded in.
But it is likely the water is in the cylinder with the leaking exhaust.
The other possibility that water is stopping the cylinder compressing.

[David Morris]

Hi David,

Glad the leak down tester proved useful. I have found them quite a good tool. You said there seemed to be leaks everywhere? But I suppose, with not being able to rotate the engine, many of the valves will be open? But No.1 cylinder seems a good place to start. Is the plug wet? Are the other cylinders showing they hold pressure, with their rocker shafts removed??

I suggest taking the rocker shaft off for cylinder No. 1 and trying giving that exhaust valve stem a gentle tap, to free the valve. You probably won't need to do any more than that?

Good hunting!

All the best,

David

[David Kemp]

I removed rocker shafts to get a measurement. Badically none of the cylinders are holding air. One you can hear the air going out the exhaust.
Others you can hear air going into the crankcase.
Oddly it started & ran well when last going.

[Srenner]

Attitude makes the difference. I think we all have had stumbles in our rebuilds.

I agree with KC that you should not put too much emphasis on the compression tests if the rings were not well seated. The one to put faith in is an open valve if no other cylinders have that hiss. Was that pushrod relatively loose?

A couple of things before tearing down. Double check your head nut torques. Perhaps a stud pulled loose. Check the inside studs for signs of water creeping past the stud/nut/washer. Remove #4 nut to see if water got past the seal.

[David Kemp]

Engine is now rotating.
Problem was the brand new ring gear has come loose and rubbed againts case.
Never seen that before.
I still have a leaky exhaust valve.
& dont know yet where water is coming from.

[David Morris]

Hi David,

Well done! We are making progress! Yes, I agree that the air getting past the rings and blowing into the crankcase is probably due to the rings not bedded-in. Does the engine rotate now? It's the water in the oil that concerns me now. Strenner mentions the head nut torques, You should only be using 35 lbs ft, not any more, despite what the book says. Also, forget what the original book says about liner protrusion. It's 0.005in max, unless you want a cracked block. But it all changes if you are lucky enough to have a really late block with 'O' rings on the liners. Did you use the NZ head gaskets and installed them as per the instructions that come with the gaskets? This is critical, but I re-torque after they have settled-in, as a few months running seems to make the re-torque necessary. I have seen engines with these gaskets where the head studs are almost back to finger tight after a few months use. I am wondering if your engine is one where one of the head bolts goes through one of the rear water outlet ports? The long studs used here get very corroded. OK, it's a typical Jowett bodge when the engines were new, but gives us headaches 70 years later!

I am thinking that the water in the sump problem has been there from the beginning, and the slight water leak has only become apparent after standing for some time? If so, it is probably only a small leak and it might respond to K Seal? If you do try this product, don't get the mickey mouse version, go for the professional version. It's a bit more expensive but works better. Search Amazon.

Slack ring gear! Right, the solution here is to pop some welds onto the ring gear/ flywheel junction, to make sure it stays in place. It's not uncommon with after-market parts.

All the best,

David

[David Morris]

Hi David, Sorry, I didn't read your latest post accurately! So, that was the cause of the engine bind. I suppose the solution would be to spot-weld the ring gear to the flywheel, and then do a little bit of grinding to the high spots on the inside of the clutch cover? It cannot be much, and might even disappear when you have the ring gear firmly attached to the flywheel. It might have just been out of round when loose?

Well done,

David

[David Kemp]

Final observations are that water seems to be coming through the push rod tubes of number one cylinder.
I will order a gasket set & then remove the cyliner head
Fix the leaking valves & reassemble .
As for ring gear I am going to inspect carefully, lock tight it on , spot weld & then use the elongated clutch housing washer method to retain it. my son has suggested using a modern starter which will push the ring gear on as opposed to the original which pulls the gear off.
All of this will mean I will concentrate on my Bradford as I want one Jowett going by Xmas.