Long story short. Frame off restored 1970 E-type. Has operated beautifully for ten years. Appropriate maintenance, etc. Recently, oil pressure is registering 60lbs at 3000rpm / 40lbs at idle. Additionally, fine oil spray from breather is coating the inside of bonnet, leakage from under oil filter canister, and leakage from dip stick hole. I have changed the oil (Castrol 10w40),changed the oil filter (paper),checked the breather tubes for obstruction, removed and cleaned all the components in the oil filter cannister and new o-ring, replaced the oil pressure guage, etc. There has also been leakage from the around the bolts on the breather housing, and from the bolts around the timing chain housing as well as around the top of the front bolts of both intake and exhaust cam covers. However, after having retorqued these bolts, this leakage has seemed to stop, although still getting some leakage around the bolts of the timing housing.

Any thoughts? Appreciate any help.

Don

Submitted by redixon@tampab… on Sun, 05/27/2007 - 09:12

It appears that you have two issues: a high oil pressure and high crankcase gas pressure, that may or may not be related.

Oil pressure is regulated by the pressure relief system (ball and spring). High pressure can only be caused by an obstruction or restriction in the pressure side of the pumping system, between pump and pressure relief system or the introduction of additional pressure from another source. PSI is PSI it can only be as high as the system will provide. Low oil pressure can be caused by any number of things mostly leaks, but high pressure has only one cause; the system is producing too much pressure. The internal clearances within the oil pump are critical; 0.006ÔÇØ between inner and outer pump lobes, 0.010ÔÇØ between outer rotor and housing and 0.0025ÔÇØ between housing and top of rotors, for example. If the pump parts were replaced not as a match set this could elevate the output pressure slightly; but pump high pressure problems are normally in the pressure relief system simply because the pump is designed to produce more pressure than required because the pressure can only be regulated down.

The crankcase breather is installed to reduce the gas pressure caused by blow-by and to a lesser extent by heat. The breather must be clean and free flowing, the filter is a fire trap to prevent flashback, etc. and will in time be clogged by the contaminated from the oil and hydrogen-carbon breakdown (sludge) provided by the escaping gases. This, if clogged will over pressurize the crankcase and force oil out of seals, gaskets, and even the dipstick tube. Excessive blow-by will also cause as similar result. It will not affect oil pressure. A new engine can have a little blow-by until the rings are seated, or excessive blow-by if the bore was increased and the incorrect rings were installed during an overhaul.

Submitted by ianc@uvic.ca on Sat, 05/26/2007 - 18:11

Have you checked the crankcase breather? When I got my car I took off the fitting on the front of the timing case and made sure it was clean, but I didn't check the pipe to the air filter. When I finally did, it was almost plugged with 'mayo'. I've done a number of things to attempt to eliminate oil leaks, so I don't know if that was important or not, but the car's not leaking as much as it used to. 1969 E Type

Submitted by djg4502@comcast.net on Mon, 05/21/2007 - 19:34

Thanks for your response to my oil pressure situation. I have now changed the oil pressure relief valve and still no luck. Any thoughts? Could the oil pump be involved, or a stuck piston/ring. Seems it may be a crankcase pressure problem. Any ideas would be most appreciated.

Thanks,

Don

Submitted by wcjssj@comcast.net on Mon, 04/30/2007 - 16:26

Edited on 2007-05-10 1:10:03

The oil filter head assembly contains a simple oil pressure relief valve consisting of a ball (Sorry, its a ball in my MG, but I see its a plug in my Jag), a spring pushing on the ball, and a seat for the ball. This valve and the viscosity of the oil determines the high oil pressure. it sounds like your pressure relief valve is not working. It is removable and you can check it out. good luck. 1967 E-type S1 FHC