Engine oils...... oil pressure sensor...I get the run around

Vanderee · Senior Member

Engine oils...... oil pressure sensor...I get the run around

kesa32 · Senior Member

Hi , lm not familiar with the Chevys, you could have a look over at forums such as " Bobs the oil guy " and see what they reckon as it's USA based and they probably know that motor well

Cheers

Aus-Kiwi · Guru

Bypass spring in oil pump too strong or shimmed too much , or plunger is sticking ? Does it run an oil cooler ? In winter .. I block off 3/4 area of the oil cooler . To keep the oil temp up where it should be .

blaze · Guru

put a remote mounted pressure switch in, then you can put it where ever you like
cheers
blaze

Jaahn · Guru

Hi Vanderee,

Seems like you are attacking the problem in the wrong way IMHO. If the oil pressure is too high and out of specifications then that should be fixed first. As already said the oil pump relief valve is faulty and should be looked at. It may cause other problems too, filter and gasket blowout. Putting different oils in the engine to suit a faulty pump seems to me to be a poor solution and not in the interest of the engines long life. hmm

As already said if you want to move the pressure switch you could put a fitting and tube in the existing port and pipe it to a new position where the switch could be mounted in a better place. It may involve an extension to the wiring also. Not a big job but perhaps not so easy to do depending on the access, but not technically difficult. Seems to me however that is fixing the symptom not the cause.

Jaahn

Vanderee · Senior Member

Thanks for te reply. I have checked the forums the USA chevy owners ; some run 10-40 semi , some 5-40 full synthetic, the oil pump and by pass spring replaced

and the galleries cleaned. GM recommends 10-40 regular oil and a oil pressure of 30 to 70. Oil cooler runs through the radiator, transmission oil cooler is in front

of radiator. Bob the oil guy recommends the GM specs for regular 10 -40. I am looking for options at the next oil change . Cheers.

Vanderee · Senior Member

Thanks for the advice. The work shop addressing the problems just said it cannot be done, so I will find a knowledgeable mechanic for a remote oil switch

install and oil bypass problem. Thanks.

Aus-Kiwi · Guru

Is the oil pressure actually that high ? Elect gauges are noterious for being out of calibration.. What is the oil temp when warm ? Has the engine been rebuilt ? It may have a high volume pump fitted ? Assembled with tighter (std) bearing clearance . 80 lb is about the limit imo . The oil pump drive can shear if any higher . Dont rev hard while engine is cold, high pressure. Check elect earths engine to chassis ? Resistance can stuff up gauge .

Aus-Kiwi · Guru

If engine is flat tappet ? I think it would be ? I suggest check oil . New oils have taken additives out so keep catilitic converters working for 100,000 miles . Flat tappet engines need zinc additives . New lighter oils dont help . High detergent oils wash off which doesnt help either . Ok off subject, just be careful you dont go into other issues . Maybe light oil with zinc additive ? youtu.be/j46pOW3ZM2k

aussie_paul · Guru

Vanderee wrote:
Appreciate some advice . Oil pressure too high in a 454 EFI Chevy big block. 50 to 80 on the gauge and the testing unit. . Chevy's do have a reputation of running high temps. The previous oil pressure sensor only lasted for two years, replaced it again after it blew out the centre, and the oil pouring out , it's mounted at the rear of the engine in a hot position. The workshop told me there is no other mounting position for the oil press.switch on the side of the engine, which would provide more airflow, but also the wiring would need alteration to the ECU and fuel pump. Changing the oil grade to HPR 10W 40 semi synthetic reduced the oil pressure to 40 to 80. Still a concern that the oil switch may pop again, and looking to some how;to mount the oil press. switch above the fuel filter as temperature also seems to be a concern and also accessibility as the mounting position is dreadful for removal and fitting. Also considering switching to HPR 5W 40 full synthetic hoping it will reduce the oil pressure further 30 to 70; hopefully. Meantime I carry a spare oil press. switch. The after market units and genuine parts are identical ; a 3 pin plastic sensor mounted on a metal base. The Holden Suburban has an identical set up i was told. Meanwhile I keep looking for oil drops ""just in case "".

i

Do you mean high temps or high pressures?

Aussie Paul. smile

T1 Terry · Guru

The later model Chev has roller tappets so the light oil won't be an issue there It the high oil pressure figure at idle cold and the lower pressure at idle hot? Or are these driving rev oil pressures?
Certainly fit a flexible oil hose extension from the current oil pressure switch position so it can be mounted some where easier to access and cool a bit away from the engine block. You will need to over lap the wire joins and solder each joint to minimise resistance so it doesn't cause computer problems further up the track.

T1 Terry

Vanderee · Senior Member

Thanks, have checked it out 10W 40 recommended.

Vanderee · Senior Member

Hi Jaahn

Yes I agree with you I will check the oil pressure manually and the by pass. The dash oil gauge could be out.

Will fit an oil switch extension so it's easy to get at. Another interesting point "the plastic tube on the oil switch sensor had distinct

plier marks on it, deep scratches and I think it was NOT installed with the proper socket, and cracked the base perhaps causing the oil

pouring out though the centre of the switch tube. This is the 3rd oil switch...hope it holds. Thanks. Cheers Keith.

Vanderee · Senior Member

Hi Aussie Paul,

Yes the engine temps are known to be high on the GM 454 so I run thermo cooling fans on radiator and a transmission

oil cooler as well. The best coolant/inhibitor/anti boil.... I found is Water Wetter other coolants run 30 degrees hotter, the airflow

is also somewhat restricted on the motor home as it runs very high temps in slow traffic. So far have not had an overheating problem.

Happy cruising.

Vanderee · Senior Member

Hi 1Terry

The cold start oil pressure is around 55 ( 800 rpm) then it drops to 40 (500 rpm) when it warms up and runs in a slower idle.

Cruising on the high way it sits on a constant 80. The GM experts say that is normal, for me it's still too high.

The P30 chassis with the 454 7.4 L EFI runs a high volume oil pump.I never had a problem till the so called experts started

fiddling with it. I will stick with the GM recommendations except for the oil switch location.Thanks.. Cheers. Keith.

PS. """I never had problems till they took out points and carbies """

Vanderee · Senior Member

Thanks for your replies guys. Never had an oil switch issue in 10 years but now they're made in China.
Give me back the points, coil and carby. Struth...they were easy fix.

Aus-Kiwi · Guru

Ok P30 so its a Workhorse chassis ? Is the oil sensor activating the fuel pump ? If it is these had issues even on the 6.5 diesel . Most used other sensors and other means of switching fuel pump . On a diesel hardly a concern .

Jaahn · Guru

Vanderee wrote:
Hi 1Terry
The cold start oil pressure is around 55 ( 800 rpm) then it drops to 40 (500 rpm) when it warms up and runs in a slower idle.
Cruising on the high way it sits on a constant 80. The GM experts say that is normal, for me it's still too high.
The P30 chassis with the 454 7.4 L EFI runs a high volume oil pump.I never had a problem till the so called experts started
fiddling with it. I will stick with the GM recommendations except for the oil switch location.Thanks.. Cheers. Keith.
PS. """I never had problems till they took out points and carbies """
__________________________________________________________________________________________________________________________________
Hi Keith
Seems like it does not want a high volume oil pump. The pressure is OK at start and hot idle but too high at normal revs. Remove the high volume pump and keep it for a couple of humdred K Kms when the motor is a bit worn. Now run the best oil of the recommended 10W-40 grade. Those very low 0W & 5W grades are not wanted in Australia (normally).
I am not sure who recommended that 80PSI was ok. Not from forums was it ???
We are not going back to the good ol' days so forget that and learn the new days. New vehicles are better but not perfect yet.
Jaahn

-- Edited by Jaahn on Sunday 23rd of September 2018 08:43:14 AM

Aus-Kiwi · Guru

In a high performance engine they run high volume pumps and larger bearing clearances due to the higher stress on bearings . More oil to lubricate better cooling . The issue is the by pass spring or tight clearance . 80psi is ok . Its the rubbish sender . The same one in my 6.5 has been replaced at 350 kpa. GM electrics have been found to be wanting around this era .,

T1 Terry · Guru

Double check the manufacturers oil specs related to high ambient temperatures because Australia has far higher ambient temps than the USA. Temperatures much below 0*C (32*F) are winter extremes over here but considered mild over there, 40*C (104*F) aren't unusual over here but considered extreme over there, so we live in an extreme climate in their view so everything needs to viewed that way when looking at specs and recommendations.

T1 Terry

Vanderee · Senior Member

T1 Terry wrote:
Double check the manufacturers oil specs related to high ambient temperatures because Australia has far higher ambient temps than the USA. Temperatures much below 0*C (32*F) are winter extremes over here but considered mild over there, 40*C (104*F) aren't unusual over here but considered extreme over there, so we live in an extreme climate in their view so everything needs to viewed that way when looking at specs and recommendations.

T1 Terry

Very true Terry. HPR 10-40 Semi Synthetic with zinc additive looks good according to specs. They do not recommend full synthetic, suppose looking back

to the old mineral oils. Some US chevies run on 5W- 30 full synth. according to what they believe; is a better oil. I am sticking with the old GM specs

10W-40.

"" I remember the old Bob Francis advert "" Goils ain't goils "" blankstare

Vanderee · Senior Member

Aus-Kiwi wrote:
In a high performance engine they run high volume pumps and larger bearing clearances due to the higher stress on bearings . More oil to lubricate better cooling . The issue is the by pass spring or tight clearance . 80psi is ok . Its the rubbish sender . The same one in my 6.5 has been replaced at 350 kpa. GM electrics have been found to be wanting around this era .,

Yes Aus-Kiwi I suppose they don't make them as they used to. The new ones are from Argentine or Korea.

All the same I am happier with a lower pressure for that reason. 60 to 65 op. temp is more comfy.

I trust the new tester is spot on. It's a Snap on supply, certified.

I got the habit of ducking under looking for oil spills. Cheers hmm

Vanderee · Senior Member

Vanderee wrote:
Appreciate some advice . Oil pressure too high in a 454 EFI Chevy big block. 50 to 80 on the gauge and the testing unit. . Chevy's do have a reputation of running high temps. The previous oil pressure sensor only lasted for two years, replaced it again after it blew out the centre, and the oil pouring out , it's mounted at the rear of the engine in a hot position. The workshop told me there is no other mounting position for the oil press.switch on the side of the engine, which would provide more airflow, but also the wiring would need alteration to the ECU and fuel pump. Changing the oil grade to HPR 10W 40 semi synthetic reduced the oil pressure to 40 to 80. Still a concern that the oil switch may pop again, and looking to some how;to mount the oil press. switch above the fuel filter as temperature also seems to be a concern and also accessibility as the mounting position is dreadful for removal and fitting. Also considering switching to HPR 5W 40 full synthetic hoping it will reduce the oil pressure further 30 to 70; hopefully. Meantime I carry a spare oil press. switch. The after market units and genuine parts are identical ; a 3 pin plastic sensor mounted on a metal base. The Holden Suburban has an identical set up i was told. Meanwhile I keep looking for oil drops ""just in case "".
>>>> How all this started... a major stuff up. A huge repair and parts bill. And....enough crap to spit the dummy.
Engine LPG injection had a pipe leak and Bundy LPG work shop fixed it, and according to diagnostics ; a leaking petrol injector. Had all the injectors serviced, plug wires, new spark plugs, new CO2 sensors, new MAP sensor, new stepper motor and TPS, new air flow sensor, because the engine kept dying and low power, ONLY on petrol..All ran well on LPG only.They could NOT find the problem. I drove it home on lpg and scratched my scalp. They also told me the in tank fuel pump runs on 50 lbs all ok. Suspicion made me have a lend of a fuel pressure tester " well.... bl...amazing on idle up to 50 lbs, on acceleration the gauge dropped to 5 lbs. hence no engine power on petrol. Replaced the in tank fuel pump and solved the problem. Runs great also on petrol; finally. Amazing, disgusting; how some mechanics cannot even diagnose fuel pressure. All parts were charged at triple cost and replaced due to ""trial and error" e.g. a $27. oil switch; charged $102. Spark plugs 18ct gold plated, Over $6000. all up for having idiots fooling around who haven not a clue. Thank god I found a new mechanic with brilliant know how and diagnostics.
PS.. A bill of $6000. plus and they could not find a simple fuel pump failure. Beyond a joke. That is Bundy LPG and auto mechanical in Bundaberg.

-- Edited by Vanderee on Saturday 22nd of September 2018 03:09:30 PM

Aus-Kiwi · Guru

Is the pressure switch also controling the fuel
Pump ? What we found the wiring inside switch wasnt up to fuel pump load even on a lift pump for a diesel . We fitted a relay . End fuel pump issues . I wouldnt be surprised if they used the same oil pressure switch / sender .. The attitude would be you have M/H BBC so you have money !!