Hello, my 1996 FZJ80 has a low oil pressure. The gauge will move only a tiny bit when the engine is cold and then it drops to 0. I checked oil pressure with a gauge and it is in fact very low. However the engine works very smoothly and the truck drives like there is no tomorrow. Before I take out the engine to work on the oil pump is there somthing I am missing that I should know. Has anyone encountered a similar problem? Any help is really apreciated. Thank you very much.
Low oil pressure, any suggestions??!?? (1 Viewer)
- Thread starter RASTA1977
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try this , maybe oil pressure sensor is loose or disconnected. start there first.
https://forum.ih8mud.com/80-series-tech/378294-dead-oil-pressure-gauge.html
https://forum.ih8mud.com/80-series-tech/378294-dead-oil-pressure-gauge.html
scottm
SILVER Star
Both my 80s showed low oil pressure, but not zero. My old Audi did show zero when warm. All three ran happily to old age like that. If there was no oil pressure there would be other indications, like a lot of valve clatter followed by the engine slowing to a stop as the moving parts weld themselves together.
Have you checked the main crank pulley? It needs to be at 304 ft-lbs. If it is not tight the oil pump slips and you loose pressure. Usually you will loose power steering as well as a symptom of the loose pulley.
I had a 96 that did this. It was caused by the pressure relief valves playing up as they were clogged up with gunk. Cleaned them out and also cleaned out the pickup strainer in the sump and all was great from then on until I sold it 100,000km later and still going strong.
Tapage
Club 4X4 Panamá
did you already check your oil press with a good mechanical gauge .?
- Thread starter
- #8
Yes we used a good mechanical gauge to measure the oil pressure and it moved only a little. I think I will try to see if there is any build up on the valves and go from there. The engine works like a charm, no weird noise and it rides like a brand new truck. Thank you very much for all your help!!!!
Tapage
Club 4X4 Panamá
jut about my curiosity .. how much PSI you got at idle @ normal operative temp .?
- Thread starter
- #10
Our gauge showed about 14 psi cold engine and after 10 min dropped to 10 psi.
Tapage
Club 4X4 Panamá
that's low ..
Not really - 10psi per 1000rpm is kinda 'norm'. Especially on an older engine that had loose tolerances to begin with.
My 97 did the same thing until I blew the engine going up Eisenhower Tunnel one night. I drove it with a very low indication for many years and had a "TLC" expert say it's normal, as long as the needle is moving "you don't need that much pressure in this engine." Geez, I was an idiot. When I had the engine rebuilt and a new pump put in, it sits about half way. Don't ignore this.
Tapage
Club 4X4 Panamá
My manual said my diesel engine must have at least 4.3 PSI @ idle @ normal operative temp and from 36 to 64 PSI @ 2000 - 3000 rpm @ normal operative temp ..
SmokingRocks
hopelessly addicted to Cruisers
I know reviving a 6 year old thread...
But I'm curious as to how an under torqued main pulley can allow the oil pump to slip?
Anyone? It doesn't seam possible to me since the oil pump is driven by a keyed gear on the crank. I guess if the pulley was so loose that it was removing. Itself from the crank it could allow some movement. But again since it's a keyed gear I would think that it's an all or nothing situation. Anyone?
My gauge is pegged even with engine off and I'm getting a funky swishing pumping noise.
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The oil pump drive gear is sandwiched behind the crank pulley. There is no key on the crank to stop it slipping so when the pulley is loose the gear slips on the crank snout. It's not a great design but it seems to be more reliable than you would think.
SmokingRocks
hopelessly addicted to Cruisers
Huh I could've sworn there was a key there when I did my rebuild. Oh well learn something every day! Thanks.
Any solutions? Currently diving into the same issue as OP
Crank pulley not torqued to spec and problems with the pressure sending unit are the most common reasons for a low oil reading. That's why the recommendation is to retorque the crank pulley nut. (Not just "tight as I can get it with my big wrench" but measured with a torque wrench).
Double-checking the pressure with a mechanical gauge will rule out the sending unit.
If both of these things are done and you still have a low pressure condition, then you may have a more sinister problem internal to the engine such as a clogged pick up screen or worn/spun rod bushings.
Double-checking the pressure with a mechanical gauge will rule out the sending unit.
If both of these things are done and you still have a low pressure condition, then you may have a more sinister problem internal to the engine such as a clogged pick up screen or worn/spun rod bushings.
I run 20/50 oil in mine, it made a big difference.
