Low Oil Pressure

[Luke_s]

Hi, So my 47TC is reading oil pressure of only 10 pounds. Things I've done:
replaced gauge - nothing
cleaned pipe to gauge - nothing
checked spin-on adapter for incorrect drilling: Appears to be correct, in that I cannot pass pencil through per suggestion on another forum
Next suggestion is to shim oil pressure relieve spring, per University Motors. This says it'll get me 5 lbs more at idle, but I'm still at just 10 lbs to begin with.
Anything else before I send off to have oil pump replaced?
Thanks,
Luke

[Steve Simmons]

Did the oil pressure drop suddenly or has it been dropping slowly over time? How many miles on the engine? Any odd noises or knocking? Any other odd behavior, overheating etc.,? It could be a worn pump or a problem with the valve.

[Luke_s]

Not entirely sure. I noticed it reading 10lbs after I became the owner. I never saw it above that. There is a recent video by a previous owner that shows it at 45lbs. This is only about less than 400 miles ago. Odometer reads 3444. In terms of noise, it's not overly clanky, sounds like other Ts that I've seen. It has not overheated and drives well. (Well, I did stop driving after the new gauge showed no change.) When my dad bought it in 2020, he had a mechanic go over it. No mention of low pressure, but he did add the spin-on adapter.

[Tom Lange, MGT Repair]

10# at idle is not great, but not impossible. What do you have when running on the road? The old saw is 10# per 1,000RPM.

While the pump is with Butch Taras being rebuilt (mgyowner@yahoo.com), pull the rocker gear, the other most likely cause of low oil pressure. The rocker shaft wears on the underside, as do the rockers. Rocker Arm Specialists are the experts here.

Tom Lange
MGT Repair

[Duncan M]

So the problem could have started when the spin on oil filter assembly was installed? People have all sorts of problems with low pressure from certain flexible lines. Problem is the inner diameter of certain flex lines is simply too small. Or have the original hard lines been retained?

Oil pump itself is quite robust on these engines. Hard to imagine a situation where flow would be reduced so much, without making a lot of noise.

[Steve Simmons]

The flexible oil line issue reduces pressure 10-20 lbs but doesn't drop the running pressure to 10. At worst it will take 60 down to 40 or so.

As far as the oil pump, it wouldn't be a matter of restriction, but actually the opposite. To much clearance from wear would reduce pressure gradually over time. A rebuild would restore it to normal. I haven't seen one wear so much as to drop pressure that low but I suppose it's possible.

Tom raises a good point. I was assuming this was running pressure. If it's idle pressure then it isn't such a big deal.

[Luke_s]

I don't recall the pressure moving up when driving. The hard lines to and from the filter are still there. A flex line was installed out of the engine to the bulkhead/gauge piping line when the spin-on was installed. I checked that line for blockage and the stream into a paper cup was there and got stronger when revving the engine, but it never registered a change on either gauge. I',m not able to say how weak or strong that stream was.

[stephen stierman]

Just to note that people like to blame the oil pumps for low oil pressure on these engines. However, as Duncan states they are indeed quite robust. When I acquired TC2911 it had 19 lbs. of oil pressure at idle and running. After I rebuilt the engine, .010 under bearings etc. and new CAM bearings, etc. etc. it had 60lbs. at speed and almost 40 at hot idle. Nothing was done to the oil pump other than clean and reinstall. It would be good to know the internal condition of the engine prior to blaming/shimming/replacing the oil pump as you may be disappointed.