I'm currently running a 1.6 CVH on bike carbs & megajolt in a kit car.

Engine was originally a 1.6i from a Sierra.

Problem I have got is that engine was running fine with 15W50 oil. Driving along oil pressure light flickered on then went off again.
Next day I went out to it, started engine and oil light didn't go off, and pressure gauge didn't show anything. Tapped oil pump with a hammer, tried again then got pressure.

I have changed the oil to a 10W40 as the old oil had been in the engine for a couple of years while I was building the kit.
Oil pressure came straight up after changing it and starting the engine.

Left it a couple of days, started it up. No oil pressure. Tried tapping with hammer, made no difference at all. All oil pressure switches are new and work fine.
When pump works it gives 1 Bar pressure at idle when warm, and basically gives an additional 1 Bar / 1000 revs as engine speed increases.

Is the pump knackered?
At a loss with it as all the time I was building the kit, rolling road, IVA test etc oil pressure has been perfect. Done 30 miles on the road and this has happened.

Any ideas appreciated.

Tapping it with a hammer is a new one on me for oil pump repairs/diagnosis .
The fact is suddenly sprung back to life the first time you did this suggests to me that you have a sticking relief valve (hex bung at the back of the pump can be removed to access this). Is it a genuine ford pump or aftermarket?

The machining on aftermarket is SHOCKING around this area and so when i've built CVH's this has always been one of the first areas i've checked. Worth a look as its a quick fix (if damage hasn't already been done - running twice with 0psi would suggest new big end bearings at least ime).

I've also cracked the pump internals before but this was on a 8000rpm~ engine so unlikely if driven sensibly.

It's the original Ford pump.

I've taken the hex cap & spring out from the pressure release valve but have been unable to get the plunger out.

I have literally only ran it for a matter of seconds when checking if the pump is going to work, so I hoping that I haven't done any damage to the bearings.

Sounds like you've diagnosed the problem then, if the plunger is stuck, it should pull out easily, if stuck off its seat oil will just bypass the engine internals.

sounds like the plunger is stuck in it,s hole.
if it looks like a bullet,stuff a piece of wood down the hole in the base and twist/pull it out

[Edited on 9/5/14 by theconrodkid]

As above, they can usually be retrieved (i've used all manner of things as the inside of the plunger doesnt need to be perfect, it only has the spring inside it).

Will definitly be the cause of your issue tho.

I have put a screwdriver down the hole and was unable to move the plunger. I assumed it was stuck right in. Although when I put the spring and bolt back in I had to compress the spring to get the bolt to do up.

I guess the only real way to tell is to split the engine and gearbox, drop the sump and take the pump off and inspect.

Is it possible to free the plunger, or should I just replace the pump and be safe?

Out of interest what clearance should I have from the bottom of the oil pickup to the sump?
Going to double check that while I'm in there.

[Edited on 9/5/14 by Davedew]

The CVH suffer from the oil strainer getting blocked causing oils pressure problems

quote:

---

Originally posted by Davedew

Is it possible to free the plunger, or should I just replace the pump and be safe?

[Edited on 9/5/14 by Davedew]

---

Try soaking it in carb cleaner or gun wash thinners.
However it sounds as if they engine is well varnished and gunged up

Thanks for all the replys guys.

I went out and had another look at the pressure relief valve tonight. Put a long bolt down into it after taking the cap and spring off, gave it a tap with a hammer and the plunger moved back in another 6mm or so.
Was stuck open just like you said.

Had a bit of a squirt around with carb cleaner / penetrating oil and the plunger seems to be moving fine now.

I recall when I changed the oil the other day that when I first started it the pressure gauge went all the way round to 7 bar!! Then dropped back. Wondering know if it over pressurised and stuck the valve open?

I've got a hydraulic tappet cleaning additive I could put in the oil which is meant to unbung things. Reckon its worth chucking it in and see how it goes?

Cold idle pressure with 10W40 oil was 4 bar, reducing to 1 bar when warm tonight. So I reckon the pump is ok, just needs a clean after having the 15W50 oil in it which used to give a cold idle pressure 5 to 6 bar.