• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Oil Pressure Slow to Rise

Share this page

G

Guy Marshall

Member
Country flag
Offline
Awhile back I bought an oil cooler sandwich plate with thermostat. I finally got around to fitting it and discover the oil pressure now takes 3-4 seconds to get to 60 psi. This is a lot longer than before as it used to get to pressure immediately.

I removed the filter and sandwich plate and I can see the filter (Wix 7074) has an anti-drainback valve and is full of oil. The lines and the cooler are both lower than the filter so they were full too. I replaced the oil filter without the sandwich plate, waited 24 hours before restarting the car, and the pressure came up immediately.

Has anyone else any experience with thermo sandwich plates causing this issue?
 
I have an oil cooler and it seems that pressure comes up faster than 3 - 4 seconds. Is the cooler mounted such that the oil in it will drain back into the pan when the engine is off?
 
Hi John,

The oil cooler is mounted lower than the filter. When I removed the s/w plate I left the lines connected to the cooler (propped up by the alternator) and I can blow in one line and oil rises in the other, so I am sure the lines/cooler remain full.

With the s/w plate ports facing forward (towards the radiator/oil cooler) the flow is on the bottom and return is on the top as I would expect.

The thermostat is open when cold, so even if the cooler / lines were blocked the oil should still circulate through the filter.

For now I have removed the thermostat and will test again tomorrow...
 
Have you tried reversing the lines on the oil cooler . They are not marked inlet/outlet on mine so flow direction through the cooler shouldn’t matter . I did notice on mine the the hoses (stainless braided) are slightly different diameters and they came as a kit from AH Spares .
 
I think you are right to be concerned, 3-4 seconds is a long time. I have a different set-up, I have a remote filter and a Mocal thermostat in the lines to the cooler which allows oil to bypass the cooler until hot so no experience with sandwich plates.
1st suspicion is the thermostat is not allowing bypass when cold, causing the cold, thick oil to have to go thru the cooler.
2nd thought is the filer, even with an anti-drain back valve, is draining some and taking a while to re-fill (one of the reasons I like remote filters is it can be mounted to hang vertical instead of horizontal and therefore cannot drain).
3rd possibility is something wrong with the sandwich plate - possibly some holes not fully/correctly aligned, or a manufacturing flaw?

I agree with mezy - make loop of hose from outlet to inlet on the sandwich plate to temporarily remove the cooler from the circuit, and time it.
 
red57 said:
I think you are right to be concerned, 3-4 seconds is a long time. I have a different set-up, I have a remote filter and a Mocal thermostat in the lines to the cooler which allows oil to bypass the cooler until hot so no experience with sandwich plates.
1st suspicion is the thermostat is not allowing bypass when cold, causing the cold, thick oil to have to go thru the cooler.
2nd thought is the filer, even with an anti-drain back valve, is draining some and taking a while to re-fill (one of the reasons I like remote filters is it can be mounted to hang vertical instead of horizontal and therefore cannot drain).
3rd possibility is something wrong with the sandwich plate - possibly some holes not fully/correctly aligned, or a manufacturing flaw?

I agree with mezy - make loop of hose from outlet to inlet on the sandwich plate to temporarily remove the cooler from the circuit, and time it.
Click to expand...
I have the identical setup, with a remote/hanging filter, and by the time I shift my eyes from the START button to the SAFETY GAUGE, it's reading >65 Lbs/Sq" so I don't think the problem is with the oil cooler (oil pressure was just as instantaneous prior to inserting MOCAL t/stat into the circuit).

I'd focus my attention on the new sandwich plate/thermostat.
 
Thanks all for your suggestions. I rerouted the oil filter lines to pass under the radiator, but I suspect the culprit was an oil filter with a dodgy non return valve. With the two changes the oil pressure comes up faster.
 
Back
Top