Welcome to our resource for MG Car Information.
Triumph TR6 - Oil Pressure
My friend Malcolm owns a 76 ( mine is a 75 ) this past week-end when he started it up there was no oil pressure reading and then the needle on the gauge slooooowly started to move 1/4 way up then jumped the last 1/8 or so. This could be a faulty gauge, or maybe that oil pressure relief valve / spring ?
Any comments welcome
Sorry I forgot to mention the car was just rebuilt last year..including all new parts in engine..I guess we can't rule out the oil pump also
|I'd suspect the gauge first. Easy to change, or just hook another up under the hood and see what you get.|
An inexpensive oil pressure gauge from Advance Auto (Canadian Tire) would tell you what you need to know.
Do the easy stuff first Charlie. At least that's MY approach.
|If he had just changed the oil where the oil passaged had drained, or if the car had been sitting for a week or more, that sounds normal. At this time of the year the oil will be colder and it will take longer for the oil to flow, therefore the needle will rise more slowly. But it should rise higher than in the summertime, a few seconds later, bucause the oil is more viscous.|
On my TR3A, the oil relief spring is to prevent excessively high pressures. If that is the case and his oil pressure was reading too high, then the relief spring would have relieved itself, (no - not like that) to avoid the oil pressure getting too high.
It doesn't sound like that was the problem.
Don Elliott, 1958 TR3A
My gauge is in the bin your welcome to borrow if it helps to test.
If during the rebuild all passages weren't cleaned junk can float around tend to migrate to slow flow areas.
Let me know. By the way you have mail
|Charlie--I'd take the relief valve apart and make sure it's not binding. It's a relatively convenient thing to do. If it's stuck open, it will short-circuit a lot of oil (and pressure) straight back to the pan.|
I agree with Rick. The relief valve is an easy-to-check job which takes five minutes.
I had a similar issue with slow to rise oil pressure as well as a significant drop once the motor warmed. I work spring was the culprit. I cleaned it and put two shims behind the spring which significantly improved the gauge readings. Knowing this, I replaced the plunger and spring (and got rid of the shims) and now have normal pressure even when warm. A thirty year old spring will sure lose its integrity when warm. Thats for sure.
Hope this helps. Although it's not a definite fix for your issue, it's an easy to rule out problem. If this doesn't prove to be the issue, I'd follow Jim's advice and check the gauge with another.
Don from Joisey
(It's windier than a goose eating chili here!)
First off Thanks for the offer Bill, but Malcolm bought a test gauge and hooked it up with a clear hose..when he started the car the oil climbed up the hose so slow we know it's not the gauge..now we try the spring test...we're getting close to the pump I think !
Try not to turn this thread into one about heaters guys !! hahaha
|Did Malcolm put in a new oil pump. The original pumps all came with a cross pin to secure the lobed part to the shaft. Over the past 15 years there is no pin in them. Instead, they take a mild steel shaft and knurl splines in the shaft, press on the lobed part and there have been stories where the splines slip and the oil pressure suddenly goes to zero !!! Logical if the lower end is not turning. I had bought my new pump in 1987 while I did my full body-off restoration. Later, oil pressure was dropping. I took it apart with 31,000 miles on it and found it was one of these with no cross pin. Also the mild steel shaft had worn about 0.003" whereas an original pump used a hardened steel shaft - so it won't wear. They can put knurling onto a hardened shaft.|
In 1997, at 111131 miles, I bought another new pump and it was the same. So I made a new steel shaft from some hardened centerless ground steel rod ($12.00 per foot from a bearing supply shop) and secured it with a cross pin.
Pressure has been OK since. With the new pump design (as original), the shaft has no wear and I've driven with it more than another 47,000 miles.
Don Elliott, Original Owner, 1958 TR3A
Yes the oil pump along with everything else in the engine is only a year old..his fuel pump also new only lasted 2 months...makes you wonder eh ??
|So after he looks at the relief valve, he may want to pull the oil pan and look at the oil pump. If it has a cross pin, the pump is OK. If it has no cross pin, it may be slipping on the splines.|
Don Elliott, 1958 TR3A
This thread was discussed between 11/11/2003 and 15/11/2003
Triumph TR6 index