Today I did my semi-annual oil change. After I put in the new oil and filter I had no oil pressure. When I removed the filter it was completely dry, as was the part of the pump I could see. I re-installed the old filter, in case my mew one was defective, but still had no pressure. The two filters are exactly the same, and the car was fine for tho 40 or so miles I drove it last Saturday. Any ideas what could be going on?
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Wierd complete loss of oil pressure
- Thread starter ColinLM
- Start date
RootesRooter
Donation Time
How long did you run the engine? I've had several instances (usually with fresh rebuilds, but sometimes after oil changes) where the oil pressure stayed at zero for perhaps a minute or more of 20-second running intervals before it finally "caught" and the needle shot up to normal psi. Some people suggest pre-lubing the oil filter and base.
I think its unlikely to be a sticking PRV. Of the half-dozen bad PRV's I've had to deal with, I've yet to have one that stuck open during initial startup. They all started sticking only when the engine & oil were warmed up. And once the pressure started dropping, it could be "cured" by briefly shutting off the engine. Upon re-start, the psi would always(!) be back to normal - but only temporarily. Depending how bad the PRV was, it could be days or as little as ten minutes between episodes.
I think its unlikely to be a sticking PRV. Of the half-dozen bad PRV's I've had to deal with, I've yet to have one that stuck open during initial startup. They all started sticking only when the engine & oil were warmed up. And once the pressure started dropping, it could be "cured" by briefly shutting off the engine. Upon re-start, the psi would always(!) be back to normal - but only temporarily. Depending how bad the PRV was, it could be days or as little as ten minutes between episodes.
In the seventies, after having just rebuilt the engine of my fastback Rapier, I went on a holiday trip from the Netherlands to Austria. After having driven quite some hours I took a 15 minutes rest on a parking place in the south of Germany. After this 15 minutes rest I started the engine and I immediately noticed that the oil pressure was at zero and stayed there. I shut off the engine and started thinking what could be the cause. In my head I went over the whole process of overhauling this engine and after some thinking I realized that although I had taken apart the complete engine I did not take apart the housing in which the PRV is installed. So what to do? I decided to give it a go with taking of the big mutter behind which the PRV is situated and with the help of a big screwdriver I sort of "pumped" the PRV a few times while hoping it would have as a result that the PRV could move freely again and....it did, because after having started the engine the oil pressure was right on again.
But what could have caused this trouble? I think that the cause was that after the process of honing the cylinders and not having washed the engine afterwards little pieces of metal must have been settled down near the PRV valve with the result of a sticking PRV. It thaugt me a lesson: after overhauling an engine including honing the cylinders: always wash the engine block!
Of course this story does not apply to Colins trouble, but never rule out a sticking PRV and it is not always possible to explain exactly why a PRV is sticking.
Regards,
Peter
But what could have caused this trouble? I think that the cause was that after the process of honing the cylinders and not having washed the engine afterwards little pieces of metal must have been settled down near the PRV valve with the result of a sticking PRV. It thaugt me a lesson: after overhauling an engine including honing the cylinders: always wash the engine block!
Of course this story does not apply to Colins trouble, but never rule out a sticking PRV and it is not always possible to explain exactly why a PRV is sticking.
Regards,
Peter
Peter, I had a very similar experience with the PRV. I DID wash the block thoroughly after rebuild, but maybe I missed some area. The sticking PRV was a recurring issue. I must have pulled it a dozen times over the next 10,000 miles or so, each time finding it just a bit sticking, cleaned it, and OK for a while. I considered it a bad design, that requires a sliding action of the piston that can so easily be stuck. I even considered designing a new one that would use a spring loaded ball instead of a sliding piston, as that would not be prone to sticking. I swapped in a couple different PRV's from my used parts bin, and eventually the problem went away. I have since assumed that it was time, mileage, and oil changes that reduced the tiny amount of "grit" in the oil that eliminated the problem.
Colin, I tend to agree with RootesRooter that it's not likely a PRV problem. A sticking PRV will not result in ZERO oil pressure, (or flow), especially with cold oil. I had a similar problem after rebuilding my engine years ago. I think you need to prime the pump a bit. Pour some oil into the filter base and quickly reinstall the filter. Maybe disconnect the 12 v lead from the distributor and crank the engine for about 30-60 seconds without starting and see if you can get a reading on the OP gauge.
Tom
Tom
Thanks to all of you for your suggestions.
The PRV seemed to work fine, piston was not stuck or overly dirty and moved with a moderate amount of pressure. We primed the system with an external pump and got WNL reading of pressure at different RPMs; however, there did not seem to be the WNL amount of oil reaching the rockers. Inspection revealed the rocker feed tube was broken. Fixed that and still not correct amount of oil feed to the rockers. So, today I ordered a new pump and assorted pipes, pickup tube and other bits from Sunbeam Specialties. I know what I'll be dong several days next week.
The PRV seemed to work fine, piston was not stuck or overly dirty and moved with a moderate amount of pressure. We primed the system with an external pump and got WNL reading of pressure at different RPMs; however, there did not seem to be the WNL amount of oil reaching the rockers. Inspection revealed the rocker feed tube was broken. Fixed that and still not correct amount of oil feed to the rockers. So, today I ordered a new pump and assorted pipes, pickup tube and other bits from Sunbeam Specialties. I know what I'll be dong several days next week.
Colin, Note that there is not normally a lot of oil going to the rockers. The oil flow is "metered" by a hole bored through the center camshaft journal, and only flows briefly once per crankshaft revolution. Not sure what you expect as the "correct amount" of feed to the rockers, but it's not a lot, just a dribble. So WNL (Within Normal Limits) is pretty small there.
Se fig 2 pg 5 of Section B of WSM 145
Tom
Se fig 2 pg 5 of Section B of WSM 145
Tom
Shannon Boal
Platinum Level Sponsor
I believe that your pump lost it's prime. This will have happened from loose clearances (wear) in the pump, end-float and backlash of the gears in the housing. You can measure that with a straight-edge and feeler guages. Lubricants with superior viscosity retention are not as prone to this as a low-quality oil might be...I like Amsoil AME 15W-40 (excellent corrosion protection for periods of dis-use; plenty of Zinc dialkyldithiophosphate for protecting flat-tappet camshaft. Enough theory, pull the pan and replace the pump, coat the gears with assembly lube before installing same.
mikephillips
Donation Time
Although if you decide to replace the pump, unless you have a later 5 main bearing engine, its not as simple as just pull the pan. The earlier 3 main bearing pump is a NLA new item, unlike the later pump. You can swap to the later pump which can still be bought new, but it requires some work since the drive gear has a different tooth count and needs to be swapped from the early pump, otherwise the distributor will go out of time. Or the 1725 cam needs to be used. Also the oil input line from the pump to the block is a different diameter, the later one being a touch bigger, so it won't screw into the earlier block. You need to modify the two lines to have one end larger and one smaller, or machine the block attachment point to fit the larger line. And you need to source the 1725 pump oil pickup since it is different and won't swap.
Just so you're aware that it isn't as simple as pull and push in a new one.
Just so you're aware that it isn't as simple as pull and push in a new one.
George Coleman
Gold Level Sponsor
I have changed oil just after a good drive around to get the oil hot, changed it out and it took about a min. for the pressure to come up. If the pump has stopped al together the motor should have been noisy.
Gordon Holsinger
Diamond Level Sponsor
I have overhauled a number of engines for our cars. On return from the machine shop I allways wash the block with warm water and a nice sudsy detergent. On assembly coat any reciprocating parts with assembly lube for the rockers I use a turkey baster and a thick oil I squirt oil on each side of the rockers where the feed line comes in. For the oil pump I pour oil into the pump and the feed line. Another thing you can do is an old mechanics trick pack the gears with thick grease or vasoline the grease blocks any air leaking around the pump gears and creates suction. I use good oil and filter for fire up check the pressure relief valve for movement. Another trick I use is I fill the oil cooler lines with oil from the filter block. I crank the motor without power to the coil until I see oil pressure then connect the coil and start
RootesRooter
Donation Time
You should start to see the first dribbles from the rockers after a couple of minutes. It may several more minutes before ALL of the rockers show oil. #8 often seems to take forever on mine!
I know a fellow whose freshly rebuilt Alpine engine refused to show ANY oil at the rockers after an hour or more of operation. Turned out the rebuild shop had mis-clocked the new cam bearing, blocking off the feed hole.
A defective oil pump is a much less likely to be the cause of no oil to the rockers, particularly if the oil pressure reading is now "WNL" when running. I improved my rocker flow by adding rubber seals to the rocker T-fitting, which was visibly seeping.
You might tell us just what pressures you're seeing, at idle and at 2,000+ rpm, cold and then fully hot.
I know a fellow whose freshly rebuilt Alpine engine refused to show ANY oil at the rockers after an hour or more of operation. Turned out the rebuild shop had mis-clocked the new cam bearing, blocking off the feed hole.
A defective oil pump is a much less likely to be the cause of no oil to the rockers, particularly if the oil pressure reading is now "WNL" when running. I improved my rocker flow by adding rubber seals to the rocker T-fitting, which was visibly seeping.
You might tell us just what pressures you're seeing, at idle and at 2,000+ rpm, cold and then fully hot.