Oil Pressure Question

[Johnnie]

Hi, I recently purchased a '92 BJ73 with the much maligned VM 2.5 TD 4 cylinder. The in-dash oil pressure gauge didn't work when I bought it so I installed an aftermarket cheapo electrical gauge. A PITA to get the original sending unit out of the block, but was able to do so. At cold idle, the gauge is reading a little over 80 psi. This seems way too high, but this is my first diesel vehicle so I'm not sure. Too high? Perhaps I should install a mechanical gauge to confirm?

Thanks!

 

[coldtaco]

What’s the ambient temperature when you did this with the new sender? What oil you using? Is the oil fresh or ready for change? Original engine or been rebuilt? If it’s any warmer than 50F then that may be a little on the high side. What’s it at when warm at idle? The colder the oil at startup generally the higher the pressure initially, but usually we are talking below freezing.

 

[Johnnie]

Temp was around 60 deg F. I assume

 

[Johnnie]

Oops, didn't finish my reply. Temp was in low 60s. I assume the po used a typical diesel-rated oil. Oil is due for a change. Engine was rebuilt approximately 30k miles ago. I didn't warm it up, but will.

 

[Loober]

You need to warm the truck up so the oil is at its normal temp, it will come way down. Mine starts way high when I first start it up, and settles down at about 13psi at idle once warm, and about 30psi at 2500rpm

 

[coldtaco]

Change the oil with proper oil (assuming 15w-40). Not knowing oil psi specs for that model VM I would assume cold oil pressure would be higher than when warm. Toyota motors have a pretty wide acceptable psi range on both ends. 80psi cold may be a little on the high side but as long as it’s not near/over 100psi it’s probably good.

 

[pradoblivious]

My 13-bt cold-starts around 60 and settles down to 25, peaking to just over 50 at 2500rpm. In the past I've experimented with that lucas oil treatment stuff and it raises my oil pressure by about 25psi

 

[sodafeld1]

Sounds high to me, I think oil filters can split open at over 100psi at the worst of times. On the 2h engine the ome oil pressure release valve can stick, some folks remedy with a longer valve and or shortening the spring a tad.

Don't know the factory gremlins in your engine and being rebuilt, who knows? more so. Certainly worth addressing with a quality oil pressure sender and gauge, good oil. The difference of the life of your engine.

 

[AirheadNut]

25psi at idle sounds a bit high, but otherwise within spec. The 3B/13B-T engine manual calls for 4.3psi or more at idle, and 36-85psi at 3000rpm. I don’t think there’s anything to worry about, but I probably wouldn’t be using the oil treatment if it has that big of an effect on pressure.

 

[JuanJ]

Hello,

It is better to have somewhat high oil pressure than low, or consistently low, oil pressure.

Cold oil is always thicker -or should I say more viscous- than warm oil. Cold oil needs more pressure to flow. Viscosity decreases with temperature, and so does pressure: warm oil needs less pressure to flow.

If you are really concerned, check your oil pressure sender and replace it.





Juan

 

[Johnnie]

Changed the oil (15w 40) and filter. After driving for several miles, oil pressure at idle is 20 psi and 60 psi at 2200 rpm, which seems reasonable. However, oil pressure when driving until engine is completely warmed up, still seems very high, e.g., 80 to 100 psi. Ambient temperature is 50ish degrees. Recommend switching to a thinner oil?

Thanks!

 

[sodafeld1]

Still would recommend a quality oil pressure gauge. 60 sounds ok at 2200rpm, 20 a bit low at idle imo, but that may be just how it is on your engine. As Taco said it is a broad range from factory specs, from memory mr toyota says 7psi is ok!. But I agree with Juan , better high than low. I calibrated a marshall mechanical pressure gauge under bonnet with in dash electric digital autometer gauge, pretty confident I get exact readings. Factory gauge tells me very little.

I get 62psi at 2100-2200rpm on old oil and 64psi with fresh oil. The lowest is 32psi after a 4 hour drive during 40c ambient with old oil at idle, 650rpm, personally don't want it lower than that, imagining happy bearings bathing and splashed with oil. I didn't like going too much over 80psi as when I explored optimum spring length on the relief valve it was very easy to hit 100+psi when revving in vicinity of 3000+rpm if the spring held the 80psi vicinity. I took some time indeed, oil pressure was quite a focus. Observing exponential psi with rpm. I would hate to pop my filter.

I think I get 50-60 psi when cold, neither too high or low. It lowers to 40psi as it warms up at idle. I like predictable clockwork, few things are.
But I have a different engine to you, being the 2h, I recieved it at 180k installed the gauges and oil bypass filter and it is now 285k, pretty happy.

I tend to use a thicker oil during summer and thinner during winter if there is an oil on special price, but always within factory spec. But honestly, I believe you may only get 2-3psi difference, which is something I guess.

Fresh carbon free oil is the optimal, I change my oil often, at the drop of a hat reason. Also, I take 500ml old oil out and replace with a fresh 500ml every tank of fuel.

An easy way to monitor your oil quality is put a bit on some clean white paper and hold to the sunlight, it shall tell you how much carbon you have in the oil.

You also may be just being paranoid pedantic, I certainly get that too! My new passengers always ask about the gauges , wires and numbers. I like them.

 

[pradoblivious]

20 - 60 sounds pretty much exactly like mine. agree 80-100 seems high even while cold and would make me nervous too.

 

[Omrib]

Hi All
HZJ73 with 520 KKM
Have low pressure readings cold and hot, on the factory gauge.
Would like to perform oil pressure check as recommended by manufacturer: pulling the sender unit and putting a mechanical gauge on a flex line.
Does anyone know what is the tread type and size for the OEM sending unit on the 1HZ?
Also, @sodafeld1 , You mentioned installing an oil bypass filter, can you elaborate as for the reasons/advantages and installation details?
Or refer to a specific thread where this info is available?
Thank you

 

[sodafeld1]

Hi All
HZJ73 with 520 KKM
Have low pressure readings cold and hot, on the factory gauge.
Would like to perform oil pressure check as recommended by manufacturer: pulling the sender unit and putting a mechanical gauge on a flex line.
Does anyone know what is the tread type and size for the OEM sending unit on the 1HZ?
Also, @sodafeld1 , You mentioned installing an oil bypass filter, can you elaborate as for the reasons/advantages and installation details?
Or refer to a specific thread where this info is available?
Thank you

I got an ultra oil bypass filter for my 2h on ebay au. It bypasses the oil return line before the oem filter with a sandwich adapter. The ultra filter is like a toilet roll which helps filter the oil much more than the oem filter. My engine oil is much cleaner, I still change at 5000km though. I also use the bypass return oil line to remove 500ml of old oil and replace with fresh through the filler hole each tank of fuel. The sandwich has two extra holes of 1/8npt and 1/8bsp for extra gauge senders if you desire, so has more than one function.

If you search 'oil bypass filter rave!' you should find it.
I like it, I like clean oil. Been using it for close to 100000km. The rubber seal for the sandwich can be replaced with a seal from a standard size oem filter if need be. Mind you, there are folks who get 6-800000km from a 2h without the bypass filter, so probably don't really need one.

It all started for me with high oil pressure paranoia in the 2h with some folks getting stuck relief valves, never happened to me as I addressed the valve, don't want it to happen. If I get aroundtoit, I would make a bridge on the internal of the rocker cover for the filtered return oil to drip on all of the rockers rather than just two of them, but they all seem happy enough.

I have a mechanical gauge on the sandwich and an autometer digital going to the dash, they calibrate which is excellent for monitoring oil pressure. Didn't want a mechanical gauge on dash for the risk of the line leaking or bursting and gushing hot oil potentially inside the car, engine bay is better for that, if at all.
Happy I did it awhile ago as the good brand gauges like marshall and autometer have nearly tripled in price since covid. I don't take much notice of the oem gauge much anymore, I think the oem was 1/8npt from memory on the 2h, but hopefully someone shall speak up there if I am wrong. Don't know the 1hz much, besides it is good. Very happy with my aftermarket oil and temp gauges, the oem gauges do not tell you much.

I can highly recommend the aussie watch dog engine guard though. It gives excellent accurate head temp, also good to know exactly when your engine is warmed to running temp.. Poos all over oem gauge. You can hear the viscous fan kick in, or watch your temp drop when your thermostat opens like digital clock work with it.

 

[Omrib]

@sodafeld1 , Thank you for the highly detailed response.
This is very helpful.
I will proceed with OEM service recommended oil pressure test, just to verify my engines health, and then purchase the aftermarket gauges.
Still contemplating about the bypass filter, may just stay with 5000 Km oil change intervals. the vehicle is intended to do arounf 2500 km per year only, so maybe every year with additives?

Also, a very uninformed question:
As I am new to Forums (of any kind) a 47 year old forum virgin...., is there any way that a new massage from an old thread is notifying anyone in the forum? or is it just that some people go through specific threads, or is there any specific order in which the threads are displayed at a specific web page according to last submitted thread post/reply?
Probably not the tread to ask this question, can you refer to any simple explanation for understanding the logic behind the forum's activity, and general rules of thumb?

Thank you and best regards

 

[Omrib]

@sodafeld1
Thank you for the highly detailed reply.
Having carefully read this and other related threads I think I know now how I would like to proceed:
I will check the actual oil pressure first by the OEM service recommended method.
Than, probably order a new OEM sending unit and an aftermarket electrical Oil-pressure and Coolant-temp' gauges with corresponding sending units.
Than think if additives and frequent (once a year) oil changes are sufficient for a 3K a year (currently 1500 Km but would like to get more fun....)

Also, as a newbie to Forums (of any kind), can you explain how relevant readers/writers are being alerted when a post is submitted to an old thread? This is probably not the thread for these questions, can you refer me to a source where I can educate myself about forums rules of thumb and basic actions?

Anyway, this had been very usefull and fun, thank you all for sharing this information.

 

[Omrib]

It seems I have double posted a reply
Sorry for that, told you I was new at this....

 

[sodafeld1]

geez , I do at least 2000km every month! No need to worry much if driving those sort of km.

I have revived discussions from 12 years ago, your posts shall sort themselves out...

 

[2fpower]

I ended up buying this kit, to eliminate any electrical sender/gauge issues, to get accurate numbers.

Amazon product ASIN B08BFNB3VP