Presure down temp up

[Thomass]

Hi all,

The last month I've traveled many kilometers in Europe, and seen almost all gazstations :driving:.
The last 4000 km, i noticed that the oil pressure, drops down to 2 on the scale ant the engine temp raises to the nearly red zone.
If i park the rig, stop the engine, check oil and cooling liquid there is nothing wrong. when i start the engine after 15 minutes, all seem to be good, pressure and temp. And after a while just doing nothing els as driving the same speed (100km/ph) the pressure goes down and the temp goes up. all i can do, to make it go away is stop the engine, wait a few minutes before i start again.

Before i start my travel, i did change the water pump for a new one, replaced the rear oil seal of the engine, checked (plastic gauge) and cleaned the oil pump. Flushed the cooling system, and refiled with a new cooling liquid.
The first 8500 km there was nothing wrong. it just started after a lunch-break at an high altitude.

Being back home, i checked everything again, pressure, blockings, oil (viscosity) and pollution, checked the bypass valves in the oil circuit, wear of bearings. :stars:
I can not find anything disturbing.
I might overlook something, but i do not know what. Before i closeup the engine again maby someone among us recognize these symptoms, and gif me a direction to look/search.
Thomass :coffee:

[4.3LXJ]

Thomas

If it shows you are over heating and you can check the fluid level, then I would suspect that your gauges might be wrong. But generally, if you heat up oil it gets thinner, or looses viscosity and will show less pressure on the gauge. Is it really getting hot?

[Thomass]

Thomas

If it shows you are over heating and you can check the fluid level, then I would suspect that your gauges might be wrong. But generally, if you heat up oil it gets thinner, or looses viscosity and will show less pressure on the gauge. Is it really getting hot?

Normally the rig runs about 100c, on high altitudes 3200 meters, the temp will heat up sooner (less atmospheric pressure) but in this case, cooling liquid raises to nearly the red spot on the gauge, oil temp is approx 92 degrees c. and the tranny oil a bit lower.
I do not think that the temperature, cools down so fast (everything is normal within minutes. first i was blaming the high altitude, but the problem remained on lower altitudes and even here in Holland (below sea-level)
So i took the engine apart again, but i can not find, nor see anything out of tune.
The temperature given are good, because the OEM gauges, gave the same as the after-marked ( with it own censors) gauges.
I'm still puzzling. This evening i even checked the oil in the lab of the nearby university, but there was no thing wrong with the oil. ????

[Mudderoy]

I don't recall ever seeing a drop in oil pressure with a large rise in engine coolant temp, but the first thing I thought of was the oil getting thin due to high heat. I wonder if you were to run straight 30 if the pressure would stay the same. It's so hot in Houston year round I ran Pensoil straight 30 for hmmm 10 years. I just recently switched to a synthetic 10w30.

[4.3LXJ]

That is a good point. I run 20W50 and keep good oil pressure even at high temps. That other stuff can just get too thin in my opinion.

[Thomass]

Well i use Kroon oil Emperol 10W-40. I use this in most of the vehicles i ever owned. If i read both your experience with an heavier kind of oil, i might have to tri this. in this engine.
later today i put the engine together again, and i will use an heavier kind of oil.
but to avoid a possible error i bought my self an new oil-pump. this because some one reminded me on the fact, that i overhauled the engine in april this year cause of this black sludge issue. and at that time i did not replaced the pump. (however it is still within oem specifications) that there is a possibility, that there are some left behind particles of this sludge what might cause a temper early blocking somewhere in the oil-path.
But the fact that the oil can become to thin is an item i did not think of. and a plausible reason of this behavior. and this will also explain the raise of temperature of the cooling liquid.
Thank you for thinking with me..:thumbsup:

Thomass

[Mudderoy]

Well keep us up to date with your progress. I know I'd like to know the reason and solution to the problem.

[Thomass]

today on the bridge I detached the oil pump once again, by meaning to replace it for an new one.
Every thing on the pump was within oem-specifications, and i had a little doubt about some being wrong with the pump.
waiting on my girlfriend who went to buy a new pump, I was playing with the pump, and put the pump drive side in a standing drill and dipped the strainer in some old oil. at the moment the pump started to rotate the oil came out the normal way as expected. but when I heated up the oil to make it thinner, the oil also came from the weld in the middle of the tube. And when i pushed to this tube the oil oozed out on that spot and less oil out of the top.

So the problem was to be found in a small crack just above the weld.
when the engine is cold, the oil is to thick to go true the crack, but when it becomes hot and thin enough, and together with the vibrations of the engine, it just got out the crack and gave less pressure.

Less oil in the engine, also creates an kind of overheating.

The new pump and a new strainer are now put in place, and the rig is once more ready to role. :driving:

I think the low atmospheric pressure on the high altitudes has started the error a bit, and I think I am lucky that I noticed this on time.
Just imaging what would happen if the tube just broke off

I also noticed that the connection between the strainer tube and the pump did leak a bit, what also might lower the pressure..

[4.3LXJ]

Great find. Persistence and skill there.

[Thomass]

Great find. Persistence and skill there.

more "luck" than wishdom :morningcoffee:

[Mudderoy]

today on the bridge I detached the oil pump once again, by meaning to replace it for an new one.
Every thing on the pump was within oem-specifications, and i had a little doubt about some being wrong with the pump.
waiting on my girlfriend who went to buy a new pump, I was playing with the pump, and put the pump drive side in a standing drill and dipped the strainer in some old oil. at the moment the pump started to rotate the oil came out the normal way as expected. but when I heated up the oil to make it thinner, the oil also came from the weld in the middle of the tube. And when i pushed to this tube the oil oozed out on that spot and less oil out of the top.

So the problem was to be found in a small crack just above the weld.
when the engine is cold, the oil is to thick to go true the crack, but when it becomes hot and thin enough, and together with the vibrations of the engine, it just got out the crack and gave less pressure.

Less oil in the engine, also creates an kind of overheating.

The new pump and a new strainer are now put in place, and the rig is once more ready to role. :driving:

I think the low atmospheric pressure on the high altitudes has started the error a bit, and I think I am lucky that I noticed this on time.
Just imaging what would happen if the tube just broke off

I also noticed that the connection between the strainer tube and the pump did leak a bit, what also might lower the pressure..

Wow nice work. I would have just replaced it and if it fixed it another mystery would have gone unsolved.

[Thomass]

Wow nice work. I would have just replaced it and if it fixed it another mystery would have gone unsolved.

That would be the case here to, but being bored on waiting on the girlfriend who went to buy a new pump made me do what i did.
If the new pump was already there, i probably, wouldn't border to investigate (more playing / fouling around).
But then, i would have never known. for me to a lesson.

Thomass

[shoker5]

Thanks for sharing, this will be remembered.