3.9 v8 low oil pressure . gurus help needed

Hi . Ive got a 3.9 v8 serp engine . I have rebuilt most of it and put loads of new parts in her . But I cant work this one out . The oil is 20/50 and gives 27psi cold and 0-17 psi when warm and idling goes to 0 psi .the engine oil light has not come on at all but shes tapping Not loud but im concerned about the pressure. Its had new rockers. Cam. Rods . Timing chain and pulleys . The oil pump was scored inside but not excessive I did put new cogs in and primed with petroleum (vasline). Im at a complete loss now and in need of some v8 gurus. I spoke to je engineering and they said it might be the new rockers and stems. Or bearings or shells. Id like to go direct to the problem insead of maybees. Its costing a fortune and I have lost tje love I had for the v8 .

If you have the concentric rotor pump then it's down to how much clearance the rotor has between the rotor and the housing it runs in.

The Rover V8 was always a low pressure engine, but obviously you need to have a working pressure at tickover to keep the lifters up.

Could be that a new front cover is needed, or try reworking the old one if you can.

The steel plate that holds the rotor assembly in place isn't the problem, it's the back of the recess that wears due to particles of carbon scoring the relatively soft aluminium face, plus the pump ports are in that face as well.

In extremis I'd try machining that face back and making up a fitted insert to provide a new wearing face.

Peter

Unfortunately, a maybe suggestion is all u will get unless some one has a crystal ball, your the one that knows the condition and history of your engine and there looking at it.
The suggestion low pressure is down to wear is valid, so starting with the pump are u sure the pump is 100%?, why the warning light is not illuminating at zero psi is strange as they are set at anything from 10 to 16psi, u have an electrical issue or a faulty switch?

Thanks guys ive looked into a new cover and omg they are expensive. Thats a good idea abt the machining the face and making a plate . So far today I have put the old rockers and shafts in. And got rid of the copy rockers . I was rwadung somewhere on here abt aftermarket parts. I will have a look at the pressure relief valve juat incase thats dud .not sure how to tell if its dud or not thou.

Ps after looking at the rockers and inside the top of the head there is definitely oil getting up there . Cant understand why the oil light hasent come on ill check th wire tom .

lightning series3 said:

Thanks guys ive looked into a new cover and omg they are expensive. Thats a good idea abt the machining the face and making a plate . So far today I have put the old rockers and shafts in. And got rid of the copy rockers . I was rwadung somewhere on here abt aftermarket parts. I will have a look at the pressure relief valve juat incase thats dud .not sure how to tell if its dud or not thou.

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20-50 oil in a 3.9

you will have check everything

Using 20/50 Halfords classuc minral
oil

We use 10W-40 diesel oil, have done for 5 years with no problem.





I may have a close-up of the internal face.

Peter

My point is 20-50 in 3.5 v8
10-40 in 3.9 and later

Due to the age and use 99% of Rover v8's have had, you cant just nail a few externals onto a tired motor and expect it to be like new.It needs to come apart,be cleaned and measured for wear,then rebuilt properly.Not a cheap quick nor easy job to do properly,nor was it a good engine from the factory... A decent rebuild would include stepped liners,but to moan about any of it is plain silly,if you need the engine to work hard for you over a decent period of time its going to cost.

Stop..before stripping engine

First i av to ask,maybe so obvious and you av done...
But..av you checked oil light works?
Av you considered oil pressure gauge fecked?

I long ago given up with elecy ones,only use capillary type..ie i get 80-100psi at 4k on mine with capiilary and 25 at tickover..but using lr landy 40-60 and 10

( aint lr engine but is in rrc)

Gauge i use is expensive not a tim

Other than that 20/50 should givevu goid pressure

IF i were you i would be plumbing in another good gauge to check


IMHO

What abt valvoline vr1 for a 3.9

Hi the oil light works and ive had a mechanical gauge give same reading as a digital one .

take your aftermarket rockers off,if you look at one you will find that the oil groove in them is like the grand canyon compared to the originals.when I rebuilt mine with them,the oil pressure was 13 psi at idle and 35 psi running,i put back the original rockers and the idle pressure went up to 45 psi(hot I might add).another way is to restrict the oil flow to the rockers by restricting the oil supply in the head,you can do this by plugging the oilway in the head with a bit of brake pipe,this will allow enough oil for lubrication but not enough to seriously drop your oil pressure.you can then refit your aftermarket rockers.(I hope that all made sense?)

I did notice the grooves on the rockers compared to my old ones and the shaft was slightly different . Im going to put back together today and see if itsade any difference . Then if not ill check the pressure relif valve .

Took pressure relief valve out and dropped the circlip that holds it in . Just spent 1 hr looking for it (hint always sweep under landy befoer you work on it ) anyway cleaned it up and it slides smoothly ish . I put a washer in the end cup to tension up the spring . So after putting it all bavk together I started her and now I get 33 psi on start up and drops to 25 when warm . I havent drove her yet so cant say . But putting the old rockers and shafts in shes definitely running quieter . Have to wait and see .

Well I drove to and from work and the tappets seem like they are getting a little more oil than before esp now ive ditched the aftermarket ones for original that was in engine thanks to you guys and face book .oil pressure now warm arround 22 psi still goes to zero when idle . So looking abit deeper and think I need to check the bottom end . I had a stethoscope on it and the front of the oil pan seems really cliky or deep tapping esp when hot ? . How easy is it to replace the parts or what partsand this time ill buy genuine parts .Ideas pls . Can it be done with engine in car .

lightning series3 said:

Well I drove to and from work and the tappets seem like they are getting a little more oil than before esp now ive ditched the aftermarket ones for original that was in engine thanks to you guys and face book .oil pressure now warm arround 22 psi still goes to zero when idle . So looking abit deeper and think I need to check the bottom end . I had a stethoscope on it and the front of the oil pan seems really cliky or deep tapping esp when hot ? . How easy is it to replace the parts or what partsand this time ill buy genuine parts .Ideas pls . Can it be done with engine in car .

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can what be done with engine in car??what parts?

Can I check the mains and replace in car once sumps of . I dont have the equipment nor level ground to get engine out . I have heard different stories