Bent push rods

[Rodger]

Hi all. Before proceeding any further to strip the engine of my Javelin, does anyone know what may have caused two push rods on one side to be quite badly bent. Started investigating after an alarming noise on trying to start the engine one day
Thanks
Rodger

[Nick Webster]

Almost certainly stuck valves. Due to their length the rods are a bit on the fragile side and unfortunately the flat four engine is a bit prone to the valves sticking after standing. They can bend just turning over a stuck engine on the handle.You write "trying to start"; has it been running before or is this a first try?

Nick

[Rodger]

Hi Nick

Many thanks for your reply, I'll look into that. The car was running previously, in fact about as well as it has. It had probably only been a couple of weeks since the previous start up. Much less time than on other occasions! I only said trying to start as obviously it failed to start. In fact I was wary of trying again as the noise was quite alarming. I can only describe as a very loud clunk. I half expected to find broken bits hanging from the engine compartment. Does that add any useful information?

Rodger

[Nick Webster]

Stuck valves are comparatively easy to check by removing the rocker cover and pushing on the rockers with a suitable piece of wood to make sure the valves move. Once moving like this, it is unlikely they would stick again if the engine is at least turned over regularly.

There is another scenario that occurs to me (especially with the clunk you describe). It is less likely but could have been a hydraulic lock. This could be water in the cylinder from a leaking head gasket or possibly petrol that has managed to pass through a carb due to the car being parked on uneven ground. Either way you could check by removing the spark plug in question and dipping it with a strip of thin card. If it comes out wet, it is cause for concern.

Nick

[Rodger]

Thank you Nick, that's very helpful. I'll check things out and let you know what I find.

[David Morris]

Hi Rodger, I think Nick is right in guessing it was caused by a sticking valve or two. You could check for hydrolocking by removing some spark plugs and checking them for water ingress. Was it exhaust valves that had the bent push rods? I find these are the most likely candidates to get stuck?

By the way, I wouldn't try and straighten the bent push rods. JCS must have loads of S/H ones, I know we sent them a stack up from Severnside Spares, when Chris Spencer kindly cleared us out. I am assuming you have an engine with mechanical cam followers? The push rods for an engine with hydraulic cam followers are different, with a little 'pip' on the cam follower end, instead of the larger ball end.

It depends on how far you want to go, but the 'golden' solution is a head-off job, and polish up the valve stems. On replacement, I recommend using some New Zealand head gaskets, the usual UK ones are not worth the effort of fitting them. You get specific instructions included with the NZ gaskets. Follow these to the letter, and I recommend re-torquing the head nuts after a couple of thousand miles. ( to 35 lb.ft, no more! ) The instructions don't mention this, but I think it is essential, as the nuts seem to work loose over some mileage. The simple solution would be to remove the rocker shafts and all the push rods, rotate the engine to ensure the pair of valves for that piston are fully closed, and give each valve stem head a tap with a light hammer, to ensure the valve is free to move. Repeat for each cylinder and, in the Haynes tradition, 'reassemble in reverse order'.

All the best, and let's enjoy this lovely spring weather!

Take care, David

[Rodger]

Hi David

Thanks for the advice. I don't actually know which rods were the culprits. I'm not doing the work myself (it's beyond my current knowledge and capabilities) and the chap who is doing it didn't note which they were before removing. I guess if it is sticking valves then we can work it out from which ones are stuck.

I'll check with JCS to see if they have any rods available. My parts list lists hydraulic tappets. Do you think the rods look like those for mechanical cam followers?

How do I get hold of the NZ gaskets? Are they available from JCS?

Many thanks

Regards

Rodger

[David Morris]

Hi Rodger, Many thanks for your reply. Yes, JCS should have the NZ gaskets in stock. They come with specific instructions regarding fitting and settling-in. I am also pretty sure they also have a supply of S/H push rods.

From your illustration, it looks like you have the earlier hydraulic cam followers. However, it it should be fairly easy to see whether you need push rods for hydraulic or the later solid tappets. If you look down the tappet chest towards the tops of the push rod cam followers, the earlier hydraulic followers have a visible spring that sits just behind the cup that accepts the end of the push rod. The later solid cam followers have no spring and a larger bronze cup, with a central larger cup that takes the ball end on the later push rods.

In taking out the push rods, its also possible that the cam followers have come out as well, as they just slide in. You can look at the ends and tell which type you need to order from JCS. If they have come out, another way to tell is to poke your finger up the bore of the cam follower drilling. If you can feel a large hole, about 5mm in diameter, then that's for the hydraulic type. If the hole is small, about 3mm, then you need the later push rods.

Hope this helps,

All the best, David

[Forumadmin]

The engine rebuilder needs educating. Push rods should be marked as to which cylinder and valve they came from on removal! That way they are bedded in to the cam follower and rocker and should require less adjustment on replacement.

[Nick Webster]

With respect to David Morris in identifying the size of the lubrication holes in the cam follower bores, it is worth remembering that in the Jowett Engineering years many early engines were reconditioned which originally had hydraulic tappets. They were rebuilt using the solid ones with associated push rods. Nothing could be done about the size of the holes so it was left. The only "downside" is potentially over lubricated cam followers. I believe that any fears that oil is being robbed to the detrement of parts elsewhere is largely unfounded.

Nick

[Rodger]

Thanks all for the information and advice. My Javelin is a 1950 Deluxe if that helps to answer the hydraulic v solid tappet question. The parts list, which references the hydraulic tappets, was issued in January 1950. I'll follow David's guidance and see if I can work out what I've got. I feel fairly sure I'll be needing some further advice in the near future.

Thanks again

Regards

Rodger

[David Morris]

Hi Rodger, Thanks for your email. I had a 1950 De Luxe Javelin, but the engine was not the original, and had mechanical tappets. After the passage of time, I would have absolutely no confidence in what the Parts List says should be present. Engines will have been swapped and even when being built Jowett's had a history of fitting whatever happened to be available on the factory floor at the time. I honestly believe that no two Javelins, despite being assembled sequentually on the production line, would be exactly the same.

I would advise you that the only method by which you can be assured as to what types of cam followers are fitted to your engine is to either look at the ends of the followers or examine the inside ends of the rods themselves. The mechanical followers have large ball ends on the push rods, whereas the hydraulic followers have quite small 'pip' ends on their push rods. They are not interchangable. There are various reasons circling around as to why Jowett's changed over to mechanical tappets. One possible cause put forward was that hydraulic tappets are not tolerant to dirt in the oil, another was that the tappets themselves were sourced from the USA, and the supply dried up, and another, which I personally think is the most likely, was that the Jowett accountants wanted to save money!

All the best, and at last the sun is shining!

David

[Rodger]

Many thanks David. Very informative. I'll check carefully before ordering replacement rods. The sun's shining here too. I just hope the car will be sorted in time to enjoy it.

Thanks again

Rodger

[Rodger]

Hi all. I have an update and a few more questions. Push rods on both sides of the engine have bent. The first photo below shows the view of the RH side (as viewed from inside the car looking forwards, which seems to be the convention used in my parts list) with the tappet cover removed. The inner two rods are bent, which I think I'm right in saying they are the inlet valve rods. None of the valves seem to be stuck so we're working on the hydraulic lock theory. The cylinder head gasket on the LH side was in a very poor state. In fact it looked like someone had attempted to use some sort of silicon sealant in the past.

1000008291.jpg

The second photo shows the 'inserts' which came out of the cam followers on the LH side. Do these confirm that the cam followers are hydraulic?

1000008290.jpg

The cam followers themselves are not sliding out. Each one comes out a few millimetres then gets stuck. Does anyone know what might be causing them to stick and/or the best way to remove them?

From comments previously made it would seem that mechanical cam followers are perhaps a better option, so I presume I could swap as long as the correct push rods are purchased with the new cam followers. Recommendations one way or the other will be appreciated.

Many thanks

Rodger

[Forumadmin]

A leaking head gasket would not bend the valve but it would crack the block if it filled a cylinder with water.
If as you say the valves do not stick then I would look at the valve timing.
Have a look at the top of the piston. Has it any indentation where the valve hit it? That will tell you the cause. No indentation then sticking valve, indentation then valve timing or a siezed cam follower .
Has any work been done on the engine since the engine was known to be running?