The V8 Owners Forum -

Need some experienced suggestions here...

Replaced head gaskets (tin -> felpro composite, heads also skimmed), oil & filter (same type), changed the manifold to an edelbrock performer + new gasket - but now I've got no oil pressure. Neither gauge (mech) or light seem to be registering.

It's a JE front cover (crank driven pump) so can't prime remotely via dizzy - have to crank the engine.

It's driving me mad! Any suggestions on where to look? What is the flow path for the oil? I've clearly done something wrong somewhere...

Have not dropped the sump yet but not sure why I would need to as things were fine before.

How much cranking have you done? Mine took about 3 minutes of cranking to get oil pressure - that is with the the oil pump filled with vaseline, the oil filter filled with oil, the oil pump filled with oil through a port and the lines to and the oil cooler I have filled with oil.

I takes a while and is a worry.

Garry

Actually fired it up (was not expecting an issue).

Beforehand I took the rockers off, poured oil down the pushrods (used camlube too). Then started it. After a couple of minutes with no pressure registering on the gauge and the orange light still on I switched off.

I was expecting it to be rattly as I had drained all the followers to get the pre-load sorted (head skim + comp gasket) with the adjustable pushrods. But things did not improve as expected...switched off. Hoping for no damage...

Where are you taking your oil pressure from ?
The two Allen key screws are NOT where you take the oil pressure from !
You need a take off on the feed of the remote filter pipe,or your filter head

Where are you taking your oil pressure from ?
The two Allen key screws are NOT where you take the oil pressure from !
You need a take off on the feed of the remote filter pipe,or your filter head

Aside from where you are reading form, it could be an instrument failure.
Pull a tappet cover off and see if there is oil in it, if the engine is pumping oil, there will be oil lying in the low spots of the head.

Take the sender out and fire it up for a moment - if oil squirts out you have oil pump pressure. With the oil pressure sender back in the entire system has to fill up and pressurise to get pressure ad in my experience that can take a couple of minutes - if you had oil coming out with the sender removed - with it back in eventually the oil will get up to the rockers where the restriction will cause the oil pressure to rise.

Garry

Blown v8 wrote:Where are you taking your oil pressure from ?
The two Allen key screws are NOT where you take the oil pressure from !
You need a take off on the feed of the remote filter pipe,or your filter head

I've got a feed off my mocal remote filter point. Pressure gauge and sender for light are Tee'd in there. Was working perfectly before rebuild with excellent pressure.

Disconnected pressure gauge and had oil coming out of this point but not squirting out... more of a dribble.

Also, difficult to tell what's happening around rockers as I had squirted oil everywhere.

Was hoping to follow flow path round the engine to trace any airlock or blockage (if any) ..I assume oil flows from sump, out of the top of the JE pump (back in at the bottom?)

My guess
Remote oil filter
Pipes have been connected the wrong way round and you are pushig oil against a non return valve in the oil filter

Check your flow and return route on the hoses.

Ian

Or the remote filter and plumbing was not pre filled with oil and the oil pump is trying to fill that first before it then fills the upper oil galleries in the engine and then develops enough pressure to be registered on the light.

But the OP states nothing changed but the filter - so how would things get crossed if nothing moved? and does not explain the dribble of flow at the switch. If nothing was touched apart from the head gaskets and the valley gasket and just a change of oil and filter it should be as it was. Assuming the oil is in the sump and not still in the can - if it was run then there should be pressure. Even during filling all the pipework there will be pressure.

I would back fill via one of the hoses and go again - unless other things were changed or removed / replaced - front pulley etc.

Thanks DS, you are right. Nothing else moved since previously working ok which is why I'm baffled..

I did initially start the engine with the car on axle stands, realised that because the car was higher at the front (the dipstick slopes backwards) when it said full this was clearly not the case. The sump pipe would've probably sucked up air initially.

I levelled the car topped up the oil but still no luck. Is it possible to get an airlock? I did undo the top oil pump output on the front cover, squirted oil in until it overflowed. Cranking gave me flow out.

But now, no pressure. Weird.

have you checked your oil pressure sender is actually working i.e. giving a signal to the gauge?

Are you 100% sure the filter is the same as the old one ?

Does it have a non return flap ?

If so, find one that doesnt and try it.

Another tip for troublesome engines, is get one of those vacuum pump thingies for removing fluids

eg this sort of thing ( or any vacuum pump really....well almost any lol )



and hook it up to an oil gallery of some sort, gauge takeoff, whatever. And pump like mad whilst cranking and the vacuum can help lift oil into the pump. I've used this with success on a few engines that otherwise just didnt want to lift the oil.

If you remove the spark plugs it it easier to crank and you will gain more revs. That sometimes helps too.