Type 4 oil pressure relief valve

Discussion in 'Mech Tech' started by Type4oval, Jul 28, 2022.

  1. Hi all please help I’m at my wits end.
    Start up oil pressure is around 60psi after about ten minutes oil temp rises to about 85c then the oil pressure drops to almost non existent and the oil temp keeps on going up and up. I initially thought the type 1 cooler in the dog house was not big enough (it’s been converted to upright cooling in a bug) so I added a large external cooler with a fan via a sandwich plate with thermostat.
    After a test run it was exactly the same and no oil was circulating to the external cooler, it’s stone cold. So I removed the thermostat in the sandwich plate and it still won’t circulate the new cooler.
    I’ve had the pressure relief valve out to make sure it moves freely but can it still be getting stuck when actually under load. Please help
     
  2. 77 Westy

    77 Westy Supporter

    The stat in the sandwich plate probably won’t start to open until 85C but there should always be some flow through the cooler even when the oil is cold.

    Is it a single or dual relief crankcase? A bit of a long shot but if it’s dual relief the oil control valve might be stuck open – or missing if the engine has been rebuilt.

    What oil grade are you using?
     
  3. I’ve tried 10/40 & 20/50 no difference. I’ve also removed the thermostat & the cooler is still stone cold but the engine is HOT. I’ve had the relief valve out and it’s moving freely but not the control valve. Does it have one it’s a Cjms code engine
     
  4. Cj
     
  5. 77 Westy

    77 Westy Supporter

    Most CJ are dual relief, some are single.

    Is this a recent problem with a new/rebuilt engine? 10w/40 is too thin, 20W/50 should be okay especially if the ambient is high wherever you are.
     
  6. The engine is new to me previous owner said he never had a problem with it getting hot. I did drive it in the guys car before I bought it and it seemed ok . It was rebuilt by him & I have all the receipts for the parts and work he carried out
     
  7. 77 Westy

    77 Westy Supporter

    Did the engine have an upright cooler conversion when used by the previous owner and what temperature and pressure were the previous owner experiencing?

    How do you know it is getting hot, where and how are you measing the temperature? 80C is a minimum oil temperature and depending on where you are and how the car is driven above 100C would not be a concern. 60psi pressure on start up is fine and will often drop to less than 10psi when hot, especially if the idle revs are low.
     
  8. Yes it was previously in a bug. My temperature gauge goes over 120c easily but my gauge may not be accurate but it is definitely hot enough to go through an external cooler even if only for an experimental exercise. So I’m thinking it is not circulating how it should as the external cooler without thermostat is stone cold while everything else is hot
     
  9. 77 Westy

    77 Westy Supporter

    The oil gets picked up from the sump by the pump flows into the filter adapter; pressure is measured after the relief valve so if you’re getting 60psi pressure there must be oil in the filter. And if there is pressure in the filter some of the oil has to pass into the external cooler – the stat doesn’t stop all of the flow. You could try cracking open the connections at the cooler to make sure there isn’t an air lock but that is very unlikely.

    I suppose the basic tuning checks have been made - valve clearance, timing, mixture?
     
  10. My main concern is why oil is not flowing & I think if I can fix that it everything else will fall in line. In the filter housing there is a ball bearing seated by a spring, could that be getting pushed open and not giving flow to the cooler?all seems fine when cold but it just points to a relief valve not working. There must be a temporary fix or test to eliminate this.
     
  11. 77 Westy

    77 Westy Supporter

    The ball in the filter housing lifts when there is a high DP across the filter (to prevent it bursting), if it’s open un filtered oil flows into the engine. Oil must be flowing because you’re getting 60psi pressure, and that’s about right for a cold Type 4 on start-up.

    I don’t know much/anything about converting to upright cooling but I’d be looking at how the normal cooler is changed to a type 1 setup.

    Incidentally, what size oil pump has been fitted? Hopefully it's not a 30mm.
     
    Last edited: Jul 28, 2022
  12. Zed

    Zed Gradually getting grumpier

    Hi,
    I did something silly once. I removed cooler and hoses from one engine and stored them with bits of paper towel stuffed in the hoses to stop dust getting in.
    Then fitted them to my new type-4 with a sandwich plate but missed one of the plugs of paper towel. Slightly different to yours it had an in line thermostat.
    Result was the oil was forced past that ball bearing valve in the sandwich pate but I had about 20-25psi driving pressure so that ball bearing valve (on mine anyway) did let a decent amount of pressure through. The cooler and all the hoses were of course stone cold. Idle pressure was fine though it didn't drop below about 10-15psi. I drove it it's first 3-400 miles like that (one trip) mildly panicking. Oops.
    Hope that's some help.
     
  13. The type 4 cooler is removed from the rear of the engine and an adapter put in its place so you can put whatever cooler you want wherever you want. In this case the po put a cooler in a doghouse fan housing running a flow & return pipe from cooler to adapter. But it’s not enough so I’ve added extra from the sandwich plate. Just don’t understand why the lines coming out of said sandwich plate are stone cold when everything else is 100c
     
  14. mikedjames

    mikedjames Supporter

    If you put the oil feed backwards through a filter with an anti drain back valve, very little oil may flow ..
    Until the filter seal blows out..

    The Mocal thermostatic sandwich plate always circulates 10% of the oil through the cooler even when cold , the thermostat only mostly opens a bypass path .

    So if the plate is cold, nothings coming out of the filter.. see my first point..

    And expect it to sieze if you dont fix it..

    If you are using the stock type 4 filter position for the filter thats very strange. But if the filter is remote then crossing the flow over is a 50: 50 chance for a random connection of hoses.
     
    Last edited: Jul 29, 2022
  15. Oil flow problem solved. It was a crappy knock off sandwich plate . I’ve changed it and all is ok now , good flow and no longer getting hot.
     
    77 Westy and Zed like this.

Share This Page