high oil pressure

[munky]

Out in the Chim today for a short trip I noticed a rather high oil pressure: 45psi at idle and 75 at cruise. I've never seen it that high before, idle is normally 20-30 as I recall. At this point I'm sure I will get replies about dodgy senders, but something else odd is happening both on cold startup and when it warms up - oil is slowly seeping from the engine block from a gasket onto the exhaust manifold and burning off. This doesn't normally happen. And the guage has behaved itself for 9 years previously. The guage still reads this high when hot, at least I left it running until the fans came on i.e. water temp was above 90 indicated, I realise oil may not be up to temp but didn't want to continue running it in case something serious is amiss.

At this point I should mention that I've only driven it once or twice over the winter (the shame, I know). I just don't drive it as much since getting the Jag. It was serviced in Sep or Oct last year, and has maybe done 100 miles if that since then. Didn't have this problem before the service.

So the big question - what are the causes of high oil pressure, if the guage is correct? Safe to drive any reasonable distance to get it checked out or not?

thanks!

[blitzracing]

The oil pressure control valve can stick, its certainly a problem on pre serp engines. Its a steel cylinder in a soft aluminium housing, and if it gets scored the plunger sticks open or closed. There is a modified valve you buy called a tadpole valve that is less likey to stick. On the pre serp engine the plunger is easy to remove, its just held in place with a bolt and spring that's removable from the oil filter casting on the outside of the engine. You can then clean up the plunger and housing with 1000 grade wet and dry paper, but make sure every thing is spotlessly clean when it goes back together. I think its much the same on the serp engines.

[spend]

[quote=munkyoil is slowly seeping from the engine block from a gasket onto the exhaust manifold and burning off.
[/quote]
Typically leaks at the rocker cover gasket.

Get a garage to check the oil pressure with a manual guage, but it might even be intermittent faulty wiring/sender. Stripping & cleaning the oil pressure relief valve is a bit more tricky on the serp engines (really need to strip a lot - I would only do it with the timing cover on the bench). 70psi is not a real worry, if your engine is designed to rev to 7000rpm then thats where the pressure relief valve should ideally be set (and the valves have no concept of rpms). Occasionally different oils will have quite different pressure characteristics, it might just be that the garage has put a very thick oil in because their normal oil falls off the cliff pressure wise when hot.

[Ribol]

I would change the oil pressure gauge sender before you start getting too technical, they can do exactly what you are describing when they pack up.

When mine packed up reading high a bit of a clue was that with the ignition on without the engine running the needle did not go fully back to where it used to when working properly.

[munky]

Thanks fellas. It's a serp engine. It's been a long time since I took an engine apart so I'll take it to someone that knows what they're doing. Meanwhile it's reassuring to know that, aside from the smoke billowing from the bonnet every time it drips and the inevitable "your TVR's on fire mate!" calls from pedestrians, nothing catastrophic should happen!

The oil seeping out is what leads me to believe that the guage is correct - it didn't leak previously. Question is, is the cause of a sticking valve (if that's what it is) likely to be lack of use over the winter, or something they did wrong on the service? It's always disappointing to find something wrong the first time one drives it after a service.

thanks

[carsy]

I think you are looking too hard at this one.

1. Rocker cover gaskets go. This will lead to your oil leak. Nothing to do with pressure.

2.Sender units are famous for giving up and giving false readings.

3. If you are getting high readings at low rpm, it wont be your relief valve.

You probably just need new rocker cover gaskets and a new sender.

[Simon says]

It you need a new sender you would be hard pushed to beat these for value for money http://www.ebay.co.uk/itm/TVR-Griff-Chimaera-Smith... I have purchased 2 of these and rectified oil pressure faults with my own car and a customers 95 Griff

[munky]

carsy said:

I think you are looking too hard at this one.

1. Rocker cover gaskets go. This will lead to your oil leak. Nothing to do with pressure.

2.Sender units are famous for giving up and giving false readings.

3. If you are getting high readings at low rpm, it wont be your relief valve.

You probably just need new rocker cover gaskets and a new sender.

all good points but both happening on the same day having never happened before? Seems unlikely, to me anyway. Timeline was like this:

1) take car for service. At this stage all guages normal and no leak.
2) drive car home from service.
3) start car about 2 months later. Oil pressure reading off the chart immediately and smoke pours out from under bonnet. Trace source of smoke to new oil leak.

Guess it could be a coincidence that leak starts and sender fails on same day, or maybe both are related to not using the car for a couple of months.

Still, seems worth changing the gasket to find out - I presume it's not too difficult?

[munky]

Simon says said:

It you need a new sender you would be hard pushed to beat these for value for money http://www.ebay.co.uk/itm/TVR-Griff-Chimaera-Smith... I have purchased 2 of these and rectified oil pressure faults with my own car and a customers 95 Griff

thanks - how easy to replace? After 9 years of owning the car it may be time I bought "the bible"..

[Simon says]

munky said:

Simon says said:

It you need a new sender you would be hard pushed to beat these for value for money http://www.ebay.co.uk/itm/TVR-Griff-Chimaera-Smith... I have purchased 2 of these and rectified oil pressure faults with my own car and a customers 95 Griff

thanks - how easy to replace? After 9 years of owning the car it may be time I bought "the bible"..

jack up couple of axle stands, a spanner a piece of piss

[spend]

munky said:

Timeline was like this:

1) take car for service. At this stage all guages normal and no leak.
2) drive car home from service.
3) start car about 2 months later. Oil pressure reading off the chart immediately and smoke pours out from under bonnet. Trace source of smoke to new oil leak.

Quite possibly leak is simply overspill from filling oil at service - the rocker covers and timing cover are buggers for hiding spilled oil.

Gauges might just be corroded contacts if the car has been left, not many grease them up for longevity.

[Dr Mike Oxgreen]

munky said:

how easy to replace? After 9 years of owning the car it may be time I bought "the bible"..

Don't think the Bible says anything about replacing the sender.

It is an easy job, although I found I could only get a short spanner in there. Being a bit of a weakling, I nearly gave up when I couldn't undo the sender - but one last try and plenty of swearing worked. Be ready to bung a rag into the hole, because oil will start (slowly) oozing out. If you're ready for it, you'll only lose an eggcup full of oil, if that. Look for the thread adapter, which will either still be in the hole or still screwed to the sender you've removed - you will need that. Then just screw the new sender (with the adapter) into the hole and tighten it up.

But as spend says, worth cleaning up the contacts first, which might save you £20.

[spend]

plushuit said:

The symptoms you descibe sounds like a stuck pressure relief valve. It too takes only a few minutes to check or replace. A tadpole is a great idea, if you can find one. The same thing will never re-occur


There is also another add-on in this area, coming from the USA's Buick 215 crowd. It allows you to adjust your oil pressure on the fly with an Allen key. Costs 10£.



p

Did you notice that he has a serpentine crank driven oil pump with the interim timing cover?

[munky]

another thought - actually from my Dad, I cannot claim it as my own - could it be that there's a blockage somewhere near the pump perhaps that is pressurising the rocker cover? Could explain both high pressure and oil seepage. Not that my dad has any particular knowledge of Rover V8s, although in his younger days he was usually to be found underneath his Healey 3000, which sadly he no longer has

[plushuit]

spend said:

Did you notice that he has a serpentine crank driven oil pump with the interim timing cover?

No. I didn't. Was it mentioned?

P.

[slideways]

munky said:

Out in the Chim today for a short trip I noticed a rather high oil pressure: 45psi at idle and 75 at cruise. I've never seen it that high before, idle is normally 20-30 as I recall. At this point I'm sure I will get replies about dodgy senders, but something else odd is happening both on cold startup and when it warms up - oil is slowly seeping from the engine block from a gasket onto the exhaust manifold and burning off. This doesn't normally happen. And the guage has behaved itself for 9 years previously. The guage still reads this high when hot, at least I left it running until the fans came on i.e. water temp was above 90 indicated, I realise oil may not be up to temp but didn't want to continue running it in case something serious is amiss.

At this point I should mention that I've only driven it once or twice over the winter (the shame, I know). I just don't drive it as much since getting the Jag. It was serviced in Sep or Oct last year, and has maybe done 100 miles if that since then. Didn't have this problem before the service.

So the big question - what are the causes of high oil pressure, if the guage is correct? Safe to drive any reasonable distance to get it checked out or not?

thanks!

Firstly have you checked to see if the oil and filter were actually changed? I have heard so many horror stories of people being charged for an oil and filter change and on inspection the old filter was still in place, does the oil still look as new?
also check the crank case breathers are clear and working, this has no bearing on oil pressure but maybe pressurising the crank case and pushing the oil out onto the manifold, also oil pressure should only be read once the oil is at operateing temps, thick cold oil will read high until it has stabilised.

[spend]

plushuit said:

No. I didn't. Was it mentioned?

P.

You are on TVR forums, 99% of Griffs & Chims are serpentine engines FYI.