OT - Rover compression tests

[christopher storey]

I hope I may be forgiven for canvassing advice here .On my newly acquired Rover 2000 TC, 82000 miles probably genuine , and engine apparently untouched, I noted poor idle. The engine has not used any appreciable amount of oil in 350 miles and there are no apparent signs of blowby into the crankcase . The inlet tappet clearances are all within limits but the exhaust ones on nos 1 and 3 cyls are 7 thou and 9 thou when they should be 11 to 13 thou . Hot full throttle compressions are 150,166,121,150, so no 3 is clearly adrift. Adding 15 mls of redex to each cyl and repeating is slightly worrying in that each reading increased by 28 to 32 , but the evenness of the increment does not suggest to me that this is a ring problem . Do I just pull the head , or should I be thinking of pulling the pistons as well ? ( if the latter I am inclined to pull the whole engine as it will need a new starter ring before long - 3 teeth missing ) . All advice , particularly about the significance or otherwise of the added redex figures, gratefully received

[PeterCrespin]

I think you're right that an even increase on all cylinders points to a non-cylinder issue with the low-reading pot. However, I'd do a leakdown test to confirm the source of the low compression. Easy enough to jury-rig (begging your pardon m'lud) if you can't buy/borrow or hite a leakdown kit.

Pete

[christopher storey]

Peter : thank you for that. I have in fact tried my home made leak down device made from a bored out spark plug, and with 100 psi applied to each cylinder, not only did the engine turn over but there was no sound of leakage from the dipstick tube which encourages me to think ( funny how you can convince yourself ? ) that it is a top end rather than bottom end problem, particularly as I could hear sounds of top end leakage in the inlet manifold

[christopher storey]

The plot thickens, unfortunately . Head off, head and gasket looked ok, certainly no overt blown gasket, nor any signs of serious valve deterioration. Bores do not feel to have any undue ridges in them . However... the no 3 cylinder, which was the suspect one, has a very strange rusty discolouration on the walls. I do wonder whether it has sat with water in it at some stage . Opinions as to cause, and/or where to go from here, will be very welcome .

[steve3.8]

Christopher ,

From what i can see ,
looking at your first picture you can see half way up the bore where the piston has been sat for a period in water with the rings marking the bore , i think thats where the damage will be ie pitting into the sidewall of the bore . Also on the first picture the seal of the head gasket looks broken by corrosion on No 3 at around 4 o clock which is next to a water feed hole .Have you took the head apart and checked the valve faces ?
Hope this helps

Steve

[christopher storey]

Steve : today I cleaned the cylinder up with abrasive , and there does not appear to be a crack , which was one of the things I feared, ( nor is there any sign of gasket failure - what appeared on the photo was just an artefact ) but the entire periphery of the bore at the ring level has a most peculiar lumpy feeling as though there has been erosion. The engine will clearly have to come out and I am working towards that . The chap who does my engines thinks it may be possible to sleeve it as with XK engines of 3.4 and 3.8 varieties . Thanks to everyone for advice

[christopher storey]

To finish this thread off, here is a close up picture of the no3 bore - like the mountains of the moon ! Block has now gone for rebore or possibly a reline