Excessive Crankcase Pressure

[simplydelboy]

Having just rebuilt the top end of my 2l Spider, 1976, I seem to be having severe high oil pressure, oil pushing out of the dipstick hole under load. It seems fine when stationary.I bought the car 15 years ago as a ground up restoration but I’m not sure whether the engine was completely rebuilt. I’m thinking that it’s probably a worn engine and maybe needs a rebore and new pistons. The top end is fine, no work needed there but can anyone recommend a reliable and hopefully not too expensive place to have the work done as I don’t have the facilities. I’m just west of Cambridge. Any idea of cost?
If anyone has experience of this and can suggest an easier alternative solution please advise. Is a pressure relief valve failure common perhaps?
Any help will be greatly appreciated
Thanks
Derek Moore

[peteracs]

Hi Derek

What does the oil pressure gauge do under load compared to normal running?

Also suggest compression test which may point to worn rings/bore which would indicate pressure buildup in the crankcase.

Also check the engine breather is not blocked.

Peter

[Nigel]

I second Peters suggestions,
but to add, your comment about oil coming up
the dipstick tube could be a symptom.

The bottom of the tube should be well above
the oil level so I wonder if there's too much oil in there?
[The dipstick is often hard to read, I've over filled mine in the past.]

Nigel

[rossocorsa]

Hi Derek

What does the oil pressure gauge do under load compared to normal running?

Also suggest compression test which may point to worn rings/bore which would indicate pressure buildup in the crankcase.

Also check the engine breather is not blocked.

Peter

I'd also suggest a leak down test

[simplydelboy]

Hi all, thanks for your suggestions. Sadly I’d done these checks already and it is as Peter suggested probably oil getting past the rings and pressurising the crankcase. And how! So it’s engine out again and I’ll see if I need to do a full rebore etc or just a hone and new rings. Thanks for your help.

Derek

[WestonE]

Hi Derek

Used Pistons are sadly normally battered with ring land excess gaps even before you do ring gap checks with new rings in the bores and find they are just too big. A re bore to oversize pistons all ready in your hands is the only sensible re-build strategy.
On the plus side you can use higher compression pistons for a power increase.

Enjoy!

PS Integrale Con rods with an oil spray slot are how you remove the risk of old conrods with oval big ends.

Eric 

[simplydelboy]

Thanks Eric, I’ve got some thinking to do. Anybody got an idea how much this would cost as I haven’t got the facilities and my ancient hands don’t have much power these days.

[simplydelboy]

Decided to bite the bullet and totally rebuild the engine. May need rebore and plus size pistons but can’t find stock in the usual places eg Betaboyz, Vicks etc. Otherwise I’ll get it honed and sleeved as the existing pistons aren’t too bad, just need a good clean where the oil had got past the rings.
Does anyone know of a secret stash?
Thanks
Del

[peteracs]

Hi Del

I just bought some pistons from a guy in Germany for a .4mm oversize build on a 2l. They came labelled as for Fiat Ritmo 1585 engine, so maybe worth searching for them rather than Beta ones? I think they will also fit 1995 Fiats such as 131. There is also discussion on these I found on various forums.

Peter