oil pressure - The update

[julians]

At the weekend I took the car to John Noble for him to have a look at my oil pressure problem ( the one where the pressure slowly drops if you hold the revs high).

 

Anyway it turns out that the bores have deep grooving on cylinders 1 & 4 and are generally worn on the rest. It looks like I'l be needing it rebored and repistoned amongst a few other things.

 

Firstly does anyone have a rough idea for what this is likely to cost, I am awaiting a quote from JN, but would like to be prepared.

 

Secondly, does anyone know someone who could supply a good zetec 2 litre short engine, this option may be cheaper than re boring etc.

 

Thirdly, does this kind of damage sound feasible, I mean the engine is not lacking any power (none that I noticed), it sounds fine, it uses some oil.

 

ANy comments gratefully received.

 

Julian

[John E]

Hello Julian,

 

Sounds like its had a hard life in a previous incarnation, probably out of a reps car. Bore wear cant affect oil pressure so it must surely be well worn in other areas, mains big ends pump etc.Try James Whiting, he does Zetec things, ring or e mail Andrew Dent cos he knows a good engine guy in Nelson. All of my engine work however was done by Roger King but I'm not sure if he's into Zetec's. There are others I'm sure who will I'm sure provide additional guidance.

 

Edited by - John E on 23 Jan 2001 16:06:36

[Steve W]

Give Chris a call at the seven workshop 01992 470480. He repaired my Zetec last year and Roger just did a great job tuning it. A new short engine from ford (mine came via raceline) is only £550 ish. For that kind of money it may not be worth repairing the old one.

[julians]

Whereabouts are the seven workshop.

 

I might give raceline a call about the engine.

 

Julian

[julians]

May I also ask how much you ended up paying in labour to have your short engine assembled and fitted in the car?

 

[StewartG]

Oh dear it looks like the old "what's wrong with it" viscous circle where if you're not careful you pay a fortune, first instalment to JN, to have the state of your engine diagnosed and you find its got so much needs doing, that it's cheaper to buy a new one. Unfortunately it's cost loads to find this out. As you've probably guessed I've been there but Chris Wheeler at the 7 workshop sorted me out relatively painlessly although it did sting a bit at the time. What I really resented was the £500ish it cost with Vegantune to find out my original engine was beyond economical repair, yes this included them partly stripping it, but it was money ultimately totally wasted as all it bought was "this engine needs binning".

I would go for a new short engine especially if you can source one at a similar price to Steve. Then let someone like Chris swap all the bits from your old engine and set it up. You have my sympathy good luck.

 

[Steve W]

The Seven workshop is in Hodesdon on the A10 just south of hertford.

As for the cost of the transplant sorry but I can't remember. I'm sure Chris will know ?

[julians]

Update Part 2:-

 

I thought that the bore scoring would affect oil pressure, but John E's comment made me think, so I rang around a few other engine builders and asked them for their opinion. The general concensus is, so what if the bores are scored , is it affecting the power? (It doesent seem to be)

 

If the power is unaffected then forget about the bores and concentrate on the real cause of the loss of pressure.

 

So with a little persuasion I now have John Noble's guys admitting that it would just be nice to fix the scoring but not essential (give or take a small bit of power).

 

They are now looking into the pressure problem like I originally asked them to do, so hopefully (fingers crossed) they'll fix the pressure problem without too much expense, and the engine will run for ages.

 

They seem to be a bit perfectionist at JN, which I guess is a good thing if you have stacks of cash and you want the worlds best engine, all I wanted was a cost effective solution.

 

[John E]

This is now an interesting subject because Julian is not the only one to have fallen foul of the buyer beware issue.

I bought my 1990 1700 SS from a reputable dealer and after 6 months decided to upgrade the engine with forged pistons, unleaded conversion etc. When RK dismantled the engine it was revealed that it was in need of a massive overhaul. I ended up with a a very fair bill for 3K. The remaining bits of the engine were not SS spec and so my spend was largely to get it back to where I thought it was in the first place plus forged pistons tufriding balancing etc. The engine is now fantastic thanks to Roger but no thanks to the seller with whom I had no come back.

I am aware of another owner living not to far from me who has had a similar rebuild bill when his engine turned out to be something other then he was lead to believe.

 

 

[John E]

Julian,

 

I have just re read part two and comment further as follows.

I'm no expert but scoring on the bores must be an indicator that something has happened, ring pick up caused by what, maybe over reving, lack of lubrication, wrong mixture etc etc.

It would be good to get an opinion from someone like Roger King who will give you the nuts and bolts of the possible cause. My engine didnt seem to be down on power but i think that Roger was surprised that it continued to run. The other issues are ;

 

What damage will ensue if something lets go big time,

Why did the Noble guys not identify the cause of the low pressure in the first place. I suspect that in order to do this a complete strip down to the bottom end is required, until that is done unless the pump is knacked then the cause can only be speculation. I think

[julians]

They think that (and this is all speculation so far, they should have proof tomorrow), the mixture is far far too rich which has caused bore wash which caused the scoring, which has also caused the petrol to mix with the oil and thin it out producing the low pressure issues.

 

They are going to get the engine tuned properley on the RR, then change the oil and see if the pressure problem is cured.

 

They suspect that if the engine continues to wear, it should just start losing power , but will not let go in a dramatic manner.

 

However they think that if the above is the cause then the engine should suffer no further wear and all should be OK.

 

I will keep the group informed of my progress, being a complete machanical idiot I do not know if any of the above sounds feasible, what does the panel think?

[Mike Bees]

Julian,

 

If it's fuel diluting the oil that's leading to low pressure, then just changing the oil & filter will restore the pressure for a while - absolutely no need for a rolling road setup to prove this. It takes time for the oil to be diluted by fuel.

 

You really don't want to be paying for a rolling road setup on an engine that might be scrapped!

 

Whole Zetecs can be had for less than 550quid, not much point it buying just a bottom end if you can have the whole thing (can be useful to have a spare cylinder head in the corner of the garage).

 

Mike

[julians]

They're not going to do a full RR on it until they have sorted the pressure problem, they are just going to lean it off, then change the oil etc, then run it again.

 

At the moment they are just using the RR instead of actually taking it for a drive.

 

Does it sound feasible for the fuel to be diluting the oil and causing this sort of pressure issue?

[EFA]

If this was the problem its likely it would not start easily an dyou woudl get a big black cloud of smoke from the exhaust whenever you booted it!

 

Unlikely.

 

Someone else ha dthis problem on a Vaux recently abd it was a weak spring in the oil pressure relief valve.

 

Unrelieved oil pressure could be higher hot and at high revs, than when your engine is cold.

 

I'd check this out if I were you....

 

 

 

Arnie Webb

Organiser- L7C Le Mans Trip

To book for this years Le Mans Trip see The Le Mans Trip Website

It really is very very very very full now!!!

[Paul Ranson]

Does it sound feasible for the fuel to be diluting the oil and causing this sort of pressure issue?

 

No.

 

Your reported problem is that the pressure drops progressively when you hold the engine at highish revs. If it was diluted oil then the pressure would be permanently low.

 

It seems to me that either the oil pump starts to suck air, (pointing to a problem with the oil draining back from the head, or with where the pick up is placed in the sump, or just a miscalibrated dipstick), or the pressure relief valve sticking open against increased flow, or with the pump itself, perhaps it starts to cavitate.

 

That's assuming that the oil pressure gauge is telling you the truth. Perhaps interference from the ignition is causing mis-readings, and the effect on gauge is to show low oil pressure.

 

Of course if the bores are scored and worn the engine is living on borrowed time. If you replace it you still need to ensure that the oil pick up/sump/dipstick combo is correct, and that the oil pressure measurement is sound.

 

Paul

 

 

Edited by - Paul Ranson on 24 Jan 2001 14:34:47

[julians]

When I spoke to James Whiting about the bore problem he said that unless the engine was losing power or using lots of oil (of which neither is true) then I shouldnt worry about the bores, and the engine should go on for ages.

 

Is this not the case?

 

 

[Slipper man]

If that's what James says, I believe him

[Paul Ranson]

Damaged bores are symptomatic. The engine may well carry on running for 10s of thousands of miles. But I'd want it right, and I think I would feel that now was the time to make it all perfect.

 

I think that until the oil pressure problems are understood you cannot really know what state the engine is in, or what damage may have been caused by the lubrication system.

 

And until it is properly setup you cannot know whether it is down on power or not.

 

I presume that John Noble will do a compression test, or preferably a leak-down test as part of the investigation.

 

Paul

[AMMO]

Julian, maybe you don't have a problem at all. I missed your previous posting so I don't know what brand and viscosity of oil you are using. What BHP does your engine make? How many miles has it done? If the oil pressure is good all of the time except when you are thrashing it, could be that as the oil gets hotter it's getting thinner and the oil pressure goes down? More revs, more horsepower, more heat. It's got to go somewhere. One of the jobs oil is intended to do is take heat away from the components. The thinner it is the faster it does it. This does not mean the engine is not being protected. Unless you are using the wrong oil. Modern oils can work up to 125 / 130 degrees centigrade without any real problems. The best oil I ever used was a product made by Castrol called SLX. It is a 0/30 and used a lot by touring car teams. We were sponsored by Castrol at a time when it had just come out and was not readily available. We used to get it for free, it used to cost £16.00 per litre (only about £9.00 now). Oil is cheaper than new engine bits. We had it analysed after every couple of races and it was perfect. The engine looked great inside too. Checked with Castrol's technical department and they agreed with me about the oil pressure. Castrol also said that there have been some oil pressure release valve changes in Zetecs. Maybe check with Ford or one of the Zetec specialists. I would use a good (not cheap)semi-synthetic or better still fully synthetic oil probably in the 10/40 range. If you thrash the car a lot change the oil often. If you are really worried about the engine and you do have a problem look at the big end shells. This is probably the first place things will start to go wrong. I'm not sure but you should just about manage to get them out in situ. One of the Zetec specialists will be able to tell you if I'm right. If the shells look OK I wouldn't worry. If they are stuffed and the crank is worn get a new engine. That's what I would do. Hope that this helps.

 

AMMO

[julians]

Thanks for the info AMMO, my first thought was that it was just the oil thinning ( I had a TVR which used to do exactly the same), however these pressure drops occur when the car has not really been thrashed much, in fact a quick blast through the first few gears would produce pressure in the 2.5 bar region rather than around 4 where I beleive its supposed to be.

 

 

[julians]

 

 

Also ...

 

Everyone else on here has suggested the pressure relief valve, but John Noble's seem very reluctant to even check this, they are almost dismissing it as if that couldnt possibly be the problem, even though I suggested when I took it in that this should probably be looked at.

 

We'll see what happens, I'll keep the group posted, I should get the car back on Saturday, so I'll know for definate then whether it has been fixed or not.

 

[Paul Ranson]

If the oil pressure is good all of the time except when you are thrashing it, could be that as the oil gets hotter it's getting thinner and the oil pressure goes down?

 

We expect maximum oil pressures to drop as the oil heats up. But I would expect oil pressure to be lowest at idle and rise with revs to a maximum capped by the pressure relief valve whatever the temperature, not fall as the revs rise, or after holding the revs above idle.

 

IOW as you spin the pump faster the pressure shouldn't drop.

 

(I wonder if the oil filter has a bypass valve that's faulty? Seems unlikely to cause this effect given everything else being in spec)

 

Paul

[julians]

Nope - not filter , this was the first thing I changed.

 

Julian

[Red SLR]

Julian

 

Did you speek to John Noble or the mechanics?

 

The best thing to do is tell John your concerns and he will listen and then take the appropriate action. They can be a bit perfectionistic ? but they do a good job.

 

If you are going back with your 7 soon let me know and I will come along.(Make enqs about engine mods and need to get a service soon.)

 

Ta

 

Simon.

 

X777CAT

[I.Mupferit]

Definitely get the pressure relief valve checked as suggested, I believe it is a well known problem with older Zetecs and relatively cheap to fix.