Help needed

SHAUNE

SHAUNE

New Member
Afternoon all
I have just fitted a new cylindr head gasket, followed all the advicegiven, thoroughly cleaned every part and surface.
labelled all parts and fitted them back in the same place they came from.

Started the engine and no issues it started sounds fine, let it walm up and bed in but when I went to drive it was really gut less.

Did a compression test (foolishly did not do one before I removed the head) and the first 3 cylinders were 75 psi the fourth 66psi.
Having looked at the hand book they should be 125psi.

This is were my limited knowledge runs out.

Any body any ideas what I need to do before I take it all to bits again
(Cylinder head torque down to specified setting)

Thanks

Shaune
 
First thing to do is check the valve clearances, if they are too tight they might be holding the valves open when hot. Did you grind the valves in while the head was off? It could be passing valves or worn rings, the closeness of the readings could also suggest that your test gauge is reading low and the fault lies elsewhere.
Another thing to note is to fit the side cover after the head is torqued down, if the head has been skimmed at any point then the holes in the cover won't line up properly and can hold the head off the block slightly.
 
Panky said:
First thing to do is check the valve clearances, if they are too tight they might be holding the valves open when hot. Did you grind the valves in while the head was off? It could be passing valves or worn rings, the closeness of the readings could also suggest that your test gauge is reading low and the fault lies elsewhere.
Another thing to note is to fit the side cover after the head is torqued down, if the head has been skimmed at any point then the holes in the cover won't line up properly and can hold the head off the block slightly.
Click to expand...
Thanks Panky
I didnt re grind the valves just cleaned everything
I will remove the side plate and re torque the head and check the valve clearances

Thsnks for the help
 
Just take the top row of bolts out on the side plate, the ones that screw into the head, before re-torquing.
 
I would also advise trying a compression test with a calibrated compression tester (someone else’s?). I have a new Sealey one but it reads low by 20psi or so.

Note 4th cylinder is often a bit less than the others as it gets hotter and wears more quickly there, especially when the water jacket is full of sand/sediment.
 
Jonathan said:
I would also advise trying a compression test with a calibrated compression tester (someone else’s?). I have a new Sealey one but it reads low by 20psi or so.

Note 4th cylinder is often a bit less than the others as it gets hotter and wears more quickly there, especially when the water jacket is full of sand/sediment.
Click to expand...
Thanks Jonathon will give that ago
 
Maybe a cylinder leakage test is needed. If you're loosing compression it's the best way to find out where it's going. You will need an air compressor though.
 
Evening all

First thanks for all your help and advice before.

Well goodish news tried another compression gauge (snap on make) and cylinder 1-2-3 read 125 psi. Cylinder 4 reads 115psi. Still running lumpy checked the plugs with one of those LED testers to see the firing cycle, all ok.
Looked at the plugs 1-2-3 were black 4 was clean . I have removed the rocker cover to check to see if every thing is going up and down ( very technical ) and it is.
Do you think one of the valves is stuck ?

Thanks
 
They’re pretty close really so compression sounds ok. Sounds like 4 isn’t running does the plug smell of petrol? - If you fire it up and pull number 4 hi tension lead off the plug (carefully or use gloves or might get a shock) and see if the lumpy running gets worse or stays the same which will show if it’s firing or not.
Maybe next switch plugs over and if the same switch the hi tension lead over from cylinder 3 to 4 and vice versa. Also check the dizzy cap to make sure 4 contact is good
 
if compression is at 115 it likely isn’t a stuck valve - it does sound most likely the spark to me.
Could also be worth checking for air leaks from the inlet manifold at number 4 but it would likely still run on the cylinder certainly when revving it
 
Thanks chaps
I have one of Martin's electronic ignition kits fitted (ran ok before) so will try what's been suggested, swap leads/plugs etc
Will give you an update tomorrow
Thanks again
 
Last edited:
Thanks again to everybody for the help and advice Ruby is now sorted and running.
I have added a few pics from the Glossop Car Show we got to last week. This is the first time shes been out for over a year20230820_104442.jpg20230820_113904.jpg20230820_113951.jpg
 
Ruby is looking fantastic and bonus Citroen DS as well :cool:
What was the problem in the end?
 
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