View Full Version : TR4/4A Was: tr4 low oil pressure

06-05-2005, 06:41 PM
Well changed out the oil/filter, tried different weights, tried a new spin on filter, just cleaned the bypass valve. tr4 still swings high at start up (past 70lbs) then once warm drops down to about 5 lbs at idle. I think the oil pump is the next target. Any thoughts on what to check. I appreciate the comments so far. /ubbthreads/images/graemlins/eek.gif
73mgb 64tr4

06-05-2005, 07:02 PM
You didn't say what weight oil your using. If your using 20-50 or better rule this out. I would also check this against another gauge to rule out false readings.
The most common place to loose oil pressure on this motor is the big bearings or the cam bores. I would put the oil pump last on my list unless you have done a recent rebuild & are sure the above is in spec.
If the motor has over 100,000 miles on it the cam bores do get sloppy & oil pours out and drops back in to the pan. Unfortunatly there is only one way to check this.
If you can run straight 40 or 50w oil and the pressure reads at least 10 psi @ idle , I would drive it through the summer & tackles this project this winter. 10 psi at idle is enough to keep things lubricated and cooled. I'm also assuming your idling at about 750-850 rpms.

06-05-2005, 07:58 PM
Tried 10w-40 then 10w-30. Do you think the gauge? It seems to read the changes as the car warms. It swings high as the car gets gas and is still cold. I believe it has 58k on the motor. trying to work it from easiest to hardest.

Geo Hahn
06-05-2005, 10:18 PM
Tried 10w-40 then 10w-30...

[/ QUOTE ]

From your prior thread [BOXoROCKS]:

Dont run 10W anything in your engine. 20/50.

[/ QUOTE ]

I thought that was spot-on. Could be the gauge, could be a dial-down of the pressure relief adjustment, could be a worn bottom end or cam bearings. You're correct to work from easiest to hardest -- 20w50 is the start for that.

06-05-2005, 10:27 PM
Try a straight weight oil like 40w or 50w. I wouldn't reccomend using this in temps under 40 deg's , but for the summer it's absolutly fine. Actually 10-30 or 10-40w oil is not recomended for summer driving, 20w-50w multi-grade is. Give this a try and let me know the results.
There are big differances in cold & hot oil temp psi readings. My cold oil pressure readings are 75psi at idle & 20psi "hot" with 10-40w oil in the winter. By hot I don't mean 30 minutes of driving, I mean an hour or more with some highway miles at 60mph or better.
The oil gauge should not react when getting gas & is not affected by electrical fluctuations, it's purly mechanical, but can be wrong.
Are we having fun yet /ubbthreads/images/graemlins/smile.gif

06-06-2005, 04:50 AM
If the oil pressure follows RPM then the presure relief valve is not regulating.Big oil loss someplace---Keoke

06-06-2005, 08:27 AM
I live in Florida where running hot is a way of life and normal oils just won't work in a brit. I finally started running Redline 20/50 full synthetic. It's exepensive as **** but worth every penny. After the second change the oil comes out nearly as clean as it went in and really holds up when it's hot. /ubbthreads/images/graemlins/savewave.gif

06-06-2005, 12:13 PM
Given the car is summer only, I'll try the 20w/50 or straight 40 or 50. Any issue on changing from regular to synthetic? While its drained this time I'll check the pump and pickup. The car did sit for a while before I began the resto process.