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Triumph TR6 - Oil Pressure Too High?

I recently went from the stock oil filter/cannister to a spin-on adapte with a Mobil1 filter. I used my regular Castrol 20W/50 and the gauge stayed at 100psi from cold for much, much longer than usual. It took about 10 minutes of driving for it to drop except at idle, which was around 50psi.
I initailly thought the filter was bad or too small so I changed it. No difference. I then went to 10W40 and things improved a bit. After 20 minutes or so, when good and warm, the pressure is 35 psi at idle, 65-70 at 2000 rpm, 85-90 at 4000. Above that the gauge pegs.
I really do not fancy having to wait 15 minutes to start to "get on it". On hard acceleration the gauge will peg.
Before I did this the gauge would read at 100 psi when cold but would drop down to 70 pretty quickly, about the same time that the temp gauge was reading near normal. When hot it always read 60psi at 2000rpm, and did not peg ever after cold start.
I am fairly positive that the adaptor was installed correctly. The inlet hole, where unfiltered oil enters the top of the filter, seems pretty small compared to the size of the original cannister.
Any thoughts? I am worrying needlessly?
Thanks!
Andy
Andy Blackley

Andy. Most TR6 owners would give an arm or leg to have that sort of oil pressure, Check it again with a mechanical gauge that is known to be good, The spin on adaptor is impossibe to fit incorrectly, and I verymuch doubt that the release valve is stuck, How many miles is on the motor?
Clive P

Clive: Thanks, but is it too much? On another forum it was recommeded not to even drive it with too high pressure. On the TR Register (UK) I checked their archives and running with high pressure didn't seem to be a big issue.
I had replaced the relief valve and spring with new ones from TRF back in May (before this).
The odometer shows 78K, but who knows? I have only owned the car for four months and the previous history is unknown. I do not have any reason to think that the gauge sudenly went south. It worked just fine immeddiately preceeding the work.
Andy Blackley

Andy,

after an engine rebuild , my oil pressure runs up to 100 psi too, with a cold start. Then, warming up, lowers to 70 psi, 50 psi at idle. When really hot, driving pressure is 50-70 psi, idle about 35 psi.
This has been so for 4 years now, no problems at all.
No oil leakage, no oil consumption, no motoring problems, spin-on installed, gauge ok (80 K at odometer).
As clive says, many TR6 club mates are impressed. My mechanic also confirms the pressure is really good, and you can drive it away straight from the cold start, easy as normal with a cold engine,if only when the engine/oil dash light is off.

Eric

Eric de Lange


I can't see why you would have a change in pressure when switching from cannister to spin on....unless there is something odd about the filter you are using. I have seen BB threads on suggested oil filters to use when using a spin on adapter and I don't recall the Mobil 1 filter as being one of them. Most people at this site use the Ford FL-400. They used to use the Fram PH3600 but I guess it has a bad reputation. You could do a search at this site and see what comes up.

If you are worried about the change in pressure just try one of those filters. It may not do anything but it's cheap enough to try.

HP
HP Henry Patterson

Andy. I rebuilt my motor last year and have about 2000 miles on it, spin on filter, Mobil 1 15/50 oil and new oil pump, I am seeing 85psi on cold start (living in Florida)cold means 75deg and driving on the Interstate constant 60psi with ambient around 95deg.The reason that I questioned your gauge is that mine was electrical and I was seeing some strange readings so changed it to mechanical and got a much more even and constant pressure reading, I am pretty sure it was the sender switch, It could be the case with your car, Its worth fitting a second gauge to compare readings and there are enough places on the block to screw into, If all seems good and you still have high O/P you could always give the rockers a treat and fit an external oil feed to the back of the Cyl head Clive
Clive P

Clive: My gauge is mechanical (my car is a TR250), and I am fairly certain that its OK.
I talked to Moss who suggested :
1. Using a FRAM PH3600;
2. Removing the adaptor and checking it for burrs, swarf etc in the passages;
3. Reinstall the old filter and see if the high readings persist.
My Labor Day weekend will be a busy one.
Andy Blackley

Andy,
Burrs in the adaptor??? It's not clear to me whether the take-off for the pressure gauge is upstream or downstream of the filter. If in front of the filter assembly, it's upstream, if behind, downstream. If the take-off is in front then the filter is restricting and you want to change it out ASAP. If behind, you now have more oil pressure than before. No big problem.
I use a Mobil 1 ML-102. The sender (which has never worked) is upstream of the filter, the gauge take-off is downstream. It runs about 80 psig cold, 50 to 70 psig hot. At idle it drops to 25 psig when hot.
Brent B

Brent: Burrs, flash, what-ever-you call it junk from the casting process may be partially blocking the passage between the block and the 90 degree filter head. This passage appears to have a relatively small cross sectional area when compared to all the space around the stock filter element.
The oil pressure gauge takeoff is in the oil gallery aft of the filter head (downstream), and the idiot light is upstream.
I suspect that something is constricting, but not blocking, oil flow. Pressure in a closed conduit is a function of cross sectional area and flow rate (liter per second, gallons per minute etc). For a given flow rate if you increase the area that the fluid flows through the pressure drops, which is why worn bearings do not hold good oil pressure. I am seeing that once the oil is hot that the idle oil pressure is the same as before or a tad higher. At low rpm the flow rate is also low, so there is not much difference. At higher rpm the pump delivers more flow and that is when I see pressure increasing to the point that the gauge pegs at 4000+rpm. This is a simplified explaination as temperature, viscosity and the roughness of the interior oilways all contribute to the "total dynamic head".
Andy Blackley

Andy - I can't see how any restriction upstream of the gauge can cause higher pressure at the gauge - that would seem to rule out resistance from the spin-on adaptor. Just the opposite - perhaps the new filter flows better (less dP per volume, and it is a constant volume /rpm pump) than the old cartridge style and now allows the by-pass valve to be more fully closed so more oil is available to flow through the gallery & bearings rather than dumping to the sump. How about that for a run-on sentence that never mentioned laminar flow?
Brent B

Henry
Many moons ago on this BBS there was a thread on oil filters with a link to a guy who took many makes of filters apart and did a comparison on them. Go to archives and key in oil filters as a search. If I recall the Fram PH 3600 was very near the top of the list for good filters. I will continue to use the Fram filter...I never changed.
Rick C
Rick Crawford

Andy,
Maybe you can swap back to the OEM canister type filter housing just to see if your oil pressure comes back down to what you feel is normal for your experience. This may help to eliminate some possible questions with the new spin on adapter. Plus it will give you a chance to examine the inner diameter of the spin on adapter as mentioned earlier.

Granted the spin on one is ideal and a good upgrade but for peace of mind maybe swapping back will help in the investigation.

Maybe the oil pressure saftey spring/piston is fouling and not working properly?

I swapped to the spin on type a while back and did notice any significant change in my oil pressure before and after the upgrade. I too am using the Fram PH3600 but have limited miles on my TR6 and it is currently back on jack stands!

Good Luck,
MRankin
MRankin

Well, I installed the PH3600 tonight and no difference. After my initial runs I kept the car running and retuned the carbs. When that was done the car was good and hot and the pressure, when very hot, past N, was back to "normal".
I also removed and checked the pressure relief valve which was fine. I had replaced it several months ago.
MRankin's suggestion is my next course of action. Perhaps I worry to much, but I do not like to see the gauge pegged past 100 psi for the first twenty minutes every time I accelerate past 4000 rpms.
Andy Blackley


Andy,

I'll give you some info I learned about the spin on adapters. It might be something to look at since nothing seems to be making sense for your situation.

Apparently there has been a history of problems with some adapters not sealing properly between the inner small 'O' ring and the outer large 'O' ring. Many times the inner O ring might not be contacting the metal surface. That is why some adapters are supplied with two inner O rings...a fatter one and a thinner one. What this could do to actual pressure I don't know. Also, check that there are not two large outer O rings in the grove in the block. Many people have mistakenly put a new one over the old one because the old one is so far into the groove that it could be overlooked. It is not a problem with the canister type filter because the inner spring mechanism compentates for it. But it is a problem for the adapters because there is no spring to compensate....Unless you do as I did. I bought the new style adapter that has an internal spring that pushes the inner 'O' ring against the block. They say it is to compensate for the difference in block machining....not to compensate for two outer O rings.

British Parts Northwest is where I bought mine. Give them a call they can explain it to you probably better than I can.

Good luck
Henry
HP Henry Patterson

I removed the adaptor today and re-installed the old cannister, with a fresh filter element. Initially no difference from before i.e. the high oil pressure syndrome was still there. After about ten minutes of driving it started to drop, and after a thorough warm up and some hard driving it was much the same before all this started. The guage still moves to 100 psi only at 4500 rpms and above, otherwise with the larger stock filter the oil pressure at speed has dropped slightly to 60 psi at 2000 rpm, which is quite good.
On examinaton there was no obvious problem with the adaptor itself.
What I did not mention in the original post was that the thrust washers had been replaced at the same time as the swap to the spin-on adaptor. It doesnt seem logical that removing that end bearing cap and installing a new Scott Helm thrust washer would have any effect on oil pressure.
At this point I will keep driving the car as I cannot see any harm from the high oil pressure. No new leaks, in fact fewer now that ther eis a fresh pan gasket. I do not see how dropping the sump and installing thrust washers could change things with the oil pressure.
Andy Blackley

There wasn't a bunch of sludge in the sump when you removed it, was there Andy?
Tom

Andy
I am not an engine guy but your comment on new Scott H thrust washers made me think. Maybe your "mains" are now running on an area of the bearings with less/no wear and this has brought up your pressure. I maybe out to lunch but you have said even going back to the old canister really did not make much of a difference. You have moved the position of the crank. The slight drop in pressure (65-70 as compared to 60 at 2000 RPM) could be the design of the oil filter itself. Did you clean the screen of the oil pump when you had the pan off? If I am correct in my thinking and hopefully some of the engine guys here will comment, then maybe it is time for some lower end work.
Rick C
Rick Crawford

Rick,

I'm not an expert myself but I do have a spare....engine that is.

I removed one of the main bearing caps and saw that you are correct. If the thrust washers had shifted the crank forward or backward then the hole in the main journal of the crank would be riding more toward the "ledge" of the channel that is cut in the center of the main bearing shell. The journal hole should be in the center of the channel. If you remember when you had your engine apart, the main bearing shells have the channel cut in them which fills up with pressurized oil and forces it out the hole in the crank journal out the the crank pins to oil the rod bearings. It would seem though that the thrust washers would have to have been installed incorectly such that one washer was quite a bit thicker that the other...thus shifting the crank. It would be a noticable shift and it would appear off center if you were to look at the journal gaps between the main bearing caps.

Henry
HP Henry Patterson

Rick C & Henry: What you suggest seems possible, but the Scott Helms bronze thrust washer was only slightly oversize from stock (.098 vs. .093), and the other was the "old" thrust washer which showed very little wear. The total end float now is about .005 instead of .010 previously.
I discussed this with a friend who has a local restoration shop and has built quite a number f engines, and he thinks that the crank did shift forward a slight amount, and it make have taken up clearance around the No. 1 bearing cap.
The sump did have some black sludge, consistent with an engine that was used infrequently. No.4 main bearing looked good, no copper showing, but I did not plastigauge it. The screen on the oil pump was just wiped off for inspection, and it looked OK.
The high pressure is being manifested when the engine is cold and a large volume of oil is being pumped. When hot things are "normal", but I am also using 10W40 oil. My buddy feels that the pressure reducing valve is doing its job, and that I need not worry about the engine being damaged. The gauge might possibly suffer however.
I had replaced the PRV assembly with one from TRF some months ago. He suggested going back to old one to see if it helps any.
Thanks for your help and thoughts!
Andy Blackley

Andy,

Based on what I saw on my spare engine if your "old" trust washer showed very little wear (still had oil grooves in it?) then I doubt the crank moved enough to make a difference. The crank would have to move substantially to start to cover the journal hole...like maybe 1/16"

Depending on how concerned you are you could pull #4 bearing cap and check to see nothing got out of whack when it went back together. You could also very easily see that the crank pin journal hole is centered in the main bearing channel. Just like I did with my spare engine...you can see the channel "notch" in the the upper main bearing with the cap removed. You can turn the crank to line up the hole to the "notch" and see that it's centered.

Good luck and let us know what you finally do.

Henry
HP Henry Patterson

An update: I reinstalled the old PRV spring, which was notably shorter than the TRF replacement, about 1/16 inch, at least.
This helps a lot. The cold pressure at speed is still high but quickly settles down to stay on the gauge. I have put several hundred miles on the car with no ill effects at all. When very hot the oil pressure is just as it was before this all started, i.e. 30 psi idle, 60 psi at 2000 rpm. So I am content. With the next oil change I will reinstall the spin-on filter.
Andy Blackley

Thanks for the update, Andy. Thoughtful of you to do that.
Tom

Yup, thanks for the update Andy. From the lower oil pressure, you must have (more) oil by-passing the engine lubrication system.
OK you engine guys out there...which is better 60 or 90 PSI?
Rick C
PS Andy, agreed, reinstall your spin-on adaptor.
Rick Crawford

Which pressure is better? Depends on whether the engine is rebuilt or not. On a worn engine, the lower psi would be fine. If I was seeing the lower number fresh off a rebuild, I would be concerned that my bearing clearances where excessive (or I had a bad oil pump!). What matters is the change in pressure over many miles of use as a wear indicator.

Some have said that the higher pressure saps useable power with no additional benefit. I guess I would agree with that as the oil pump is a positive-displacement device and it's the oil volume (flow rate) that counts (same whether high or low pressure). Remember, the engine bearings aren't "supported" by oil pressure; as long as a film of oil is present, the system is working.

Rick O.
72 TR6
Rick Orthen

I recall that I was able to adjust the oil pressure on my '65 TR4 by turning a nut at the oil filter take-off.It was a long time ago but I believe I'm correct.
Is there not the same cability on the 6? I recall that changing the filter on my 4 was a hassle, and I assume that the 6 is similar, but other than that, what are the inherent drawbacks in the stock filter arrangement for both 4 and the 6?
dennis

Dennis: You are correct in that you can adjust the PRV on the filter head of the older TRs, but not the sixes. The spring length that I mentioned in my posts does not affect pressure while running, only the pressure it takes to by-pass, so playing with spring lengths does nothing to improve hot engine oil pressure.
The draw back to the stock six cylinder filter is that being horizontal and relatively large in diameter it is: 1. messy and difficult to remove and re-install. I had to unbolt the slave cylinder to get clearance;
2. it takes longer for initial oil pressure to develop on start-up, since most of the oil in the filter drained out and the filter must be filled before oil reaches the oil gallery and thence the bearings.
Andy Blackley

Just as a side note on oil pressure. The TR6 owners manual that came with the car states oil pressure to be between 40 and 60 psi warm at road speed. They don't give a spec for idle oil pressure. My Malibu boat with a V8 engine...the owners manual states oil pressure to be 30 to 50 psi at 2000 RPM warm and greater than 4 PSI idle. My boat pressure guage is always around 40 PSI at both idle and 2000 RPM. Must be a different kind of pump than our 6's.

Sometimes I think we (I) worry needlessly about the exact reading on the guage on our 6's. If I'm cruising down the road and engine hot...I'm happy if I see the needle at the 1/2 way point. I'm even happier when I bring it up to 2500 RPM and see the needle go higher.

HP
HP Henry Patterson

Andy,

What year is your 6? On my 73 they put a hole in the inner fender so you can get a socket and extension in there from behind the front wheel. That's how I installed my filter adapter. I don't know what year they started putting the hole in. I believe earlier cars didn't have it.

Henry
HP Henry Patterson

This thread was discussed between 31/08/2005 and 16/09/2005

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