low oil pressure

[swiftcarl]

Hi all

I've just purchased a 1991 HDT 80 series and think i may have low oil pressure. At Idle it sits just off the L and at cruising speed just about the 3rd marker. Is this normal or is it low? if its low what could be the cause?

Many thanks

 

[Firewout]

Hi Carl and welcome to the club.
The oil gauge in the dash is not known for being very accurate...
For your piece of mind, you can hook up a pressure gauge and check it out.
In my cruiser, the pressure also sinks quite low on the gauge when idling, especially when hot.
Btw, have the big end bearings been checked/replaced?

 

[Bmonck]

My 1992 HDT also idles at about 1/3. When driving it moves between 1/3 and 1/2.

 

[Higgy]

What's your mileage?.... Mines dine 330,000 miles, and im quite happy that the gauge moves at all..... But like as been said, The pressure gauge is not the most accurate

 

[Iwan]

My pressure gauge drops to zero when you exit off the motorway. Fitted a Y piece one outlet for the factory sender and a pipe to a gauge in the cabin.

You get the real reading and compare the false reading from the factory setup..

 

[Chris]

When was the last time you had a car with an oil pressure gauge? Is it something that you've missed? Most cars now don't even have a temp gauge. The niggle with the gauge in the 80 is that it reads - a bit. If it didn't move you'd just say, hey it's broken. Who cares. Problem is that it reads then falls at which point everyone panics. Just pull the wire off the sender on the block and forget about it.

 

[Towpack]

As said, the OEM gauge isn't 100% reliable. If it worries you that much just check the pressure with a decent secondry gauge and confirm it's in spec, then forget it. My old Disco had no OP, turbo boost or EGT gauges and I thrashed that up and down the motorway towing the boat when I had it and never gave it a second thought.

 

[Iwan]

I believe when an engine is tested they hookup the direct oil line gauge to give an idea of how tight the tolerances are in the bearings. This on a cold startup will reveal that the pressure will be twice the amount of the warm reading on idle.

So with a 1hdt that is unknown it's not a bad thing to have an accurate knowledge of oil pressure.

 

[swiftcarl]

Thanks for the warm welcome guys, much appreciated.

This is the oil pressure on idle it moves up to the 1/3rd line when i'm cruising. I might book it in to get the bearings checked. is it a big job?

 

[chapel gate]

yeah, a oil pressure gauge is a pretty archaic way of monitoring the condition of an engine. back in the day when pretty much every bearing was on its last legs at 60000 miles they may of been useful.
on a 1HD T, even with BEB self destructing, the gauge will be telling you life is still good..

on the three different cav SRIs that i had owned, every one let go on the bottom end. sure, the oil pressure warning light gave me notice there was a problem, all 1.5 seconds of it before the dreaded rattle started..

an EGT gauge and secondly a coolant temp gauge, are the best gauges you could install IMO.

 

[chapel gate]

mine can be on zero at idle after prolonged driving.

no point in checking the BEBs. just change them. cheap and easy job.

 

[Chris]

I think that you'll find the BEBs contribute very little to the oil pressure in reality. I am not sure how much the 12v power plant was affected by those rogue BEBs in Oz though. Worth getting a view from down under. But as a precaution, yeah, just change them.

 

[IRLGW]

I have to say I never saw any correlation between Beb's and oil pressure unless a Conrod popped out the side. The oil is thicker when cold so pressure is initially higher on startup. I would say it's more useful as an indication of oil level if one sub-conciously calibrates the peripherial of their sights to it.. mind you, if you start up cold and it doesn't rise then probably best to turn it off and ring the Samaritans..

 

[frank rabbets]

I cleaned the oil pressure sender contact wire terminals on mine and got a higher reading. Previously I had run a test with a mechanical gauge and pressure was OK.

Not much correlation between bearing wear and oil pressure anyway in my opinion especially on engines post 1960's. I've had engines with worn out main bearings showing normal pressure. Thing is the oil pressure relief valve can close up to compensate for difference.

I had a crank shaft beak across the front web on another engine. That's the equivalent in human terms of needing a tourniquet but oil pressure did drop from 45 psi to about 10 psi. I was 45 miles, 1/2 way up the motorway to Manchester to see my new girlfriend but had to turn back and made it home. Next day had the sump off to check bearings and on using the front web as a tab washer lever point the whole front of the crank moved forward. Needed a 1/2 engine as a new crank was more money. Phoned the main BMC dealer and a little man arrived in a Morris Minor van with the 1/2 engine and bill. Paid cash and off he went. BTW all bearings on the broken crank were perfect.

 

[Iwan]

Just to note I didn't go out to buy the gauge and pipe etc.. I was driving to North Germany and the gauge was dropping out on exiting the autobahn. Coupled with the previous problem of a scored beb (no5) six months earlier and having no roadside recovery... was getting worried.

I traveled to see my mates from cruiserworld in The Neatherlands and Laurens had the kit that He took off a project 61 and said "I really don't need this, but be interesting what's the score or to know with yours!". So fitted it relieved the worry and it is still in the truck to this day! A pipe ziptied to the gear lever and have kept an eye on it on startup... The most important thing is to let it idle for upto 5 seconds for the needle to move, longer if real cold before you rev it or drive off..

Just an observation from having one fitted..

 

[IRLGW]

I cleaned the oil pressure sender contact wire terminals on mine and got a higher reading. Previously I had run a test with a mechanical gauge and pressure was OK.

Not much correlation between bearing wear and oil pressure anyway in my opinion especially on engines post 1960's. I've had engines with worn out main bearings showing normal pressure. Thing is the oil pressure relief valve can close up to compensate for difference.

I had a crank shaft beak across the front web on another engine. That's the equivalent in human terms of needing a tourniquet but oil pressure did drop from 45 psi to about 10 psi. I was 45 miles, 1/2 way up the motorway to Manchester to see my new girlfriend but had to turn back and made it home. Next day had the sump off to check bearings and on using the front web as a tab washer lever point the whole front of the crank moved forward. Needed a 1/2 engine as a new crank was more money. Phoned the main BMC dealer and a little man arrived in a Morris Minor van with the 1/2 engine and bill. Paid cash and off he went. BTW all bearings on the broken crank were perfect.

You never said what happened to the new girlfriend, was it meant to be a cliff hanger?