Oil pressure??

Oil pressure??

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Discussion

cejsmith

Original Poster:

167 posts

255 months

Sunday 23rd August 2015
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Can someone tell me what the correct idle and running oil pressure should be on a 5l rv8.

ClassiChimi

12,424 posts

148 months

Sunday 23rd August 2015
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Running pressure about 40 psi, idle not much less than 30 psi that supposing your gauge is accurate? I had an intermittent connection to my oil sender so sometimes my gauge would go up and down so if you have erratic readings maybe check the connections at the sender.

cejsmith

Original Poster:

167 posts

255 months

Sunday 23rd August 2015
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The reason I ask is I just went to see a car and at idle is showed just under 30 but never really increased with revs.

ClassiChimi

12,424 posts

148 months

Sunday 23rd August 2015
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Just under 30 psi at idle is very good, it should go up to 40-50psi at say a constant 3000 revs so did you build the revs up and hold for a few moments, ( let the gauge catch up sort of thing ) was there any audible tapping or metallic noise coming from the engine, any smoke or smell of oil etc, oil leaks stuff like that, when was it last serviced and what does the owner say regards oil pressure readings.

cejsmith

Original Poster:

167 posts

255 months

Sunday 23rd August 2015
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No strange noises, the car has done over 110k miles ( it must of had a rebuild by now I would have thought) , but as I said the gauge didn't really move.also what should be the running temp be ?

phazed

21,844 posts

203 months

Sunday 23rd August 2015
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You really can't trust the gauge and sender, they are a guide only.

Far better to check with a proper mechanical gauge straight off the sender pick up point.

cejsmith

Original Poster:

167 posts

255 months

Sunday 23rd August 2015
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phazed said:
You really can't trust the gauge and sender, they are a guide only.

Far better to check with a proper mechanical gauge straight off the sender pick up point.
Can't really do that on a test drive 😩😩

ClassiChimi

12,424 posts

148 months

Sunday 23rd August 2015
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Fans should kick in at about 90 degrees.
If the engines been re built there should be evidence,,,, or assume it's done the milage recorded, it's not that unusual to get one doing that kind of milage but a 5.0 ?
Both temp and oil pressure gauges can give erratic readings so just let the engine idle until fans kick in and most importantly go off again and read the gauge at that point,,,, try and drive the car in traffic and keep listening for the fans to kick in/ out,,, when stopped I'd check top rad hose to see if it seems to be bulging etc. if the car drives and smells ok during a reasonable period,, say 20 mins and the temp and oil gauges are reading regular then it should be ok... At least on the water side !

davelittlewood

306 posts

132 months

Sunday 23rd August 2015
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My first gauge showed 20 running and just over zero at tick-over. Got replaced as it was almost useless like this.
Second gauge showed 40 running and about 30 at tick-over, then it failed.
Third gauge shows 30 running and about 15 tick-over.

Same engine, no real change in oil pressure just different gauges.

If your gauge is showing almost nothing on tick-over then swap it and see what happens.

You don't need to be driving the car to test the oil pressure with another gauge, just rev it up.

Bassfiend229hp

5,530 posts

249 months

Sunday 23rd August 2015
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cejsmith said:
No strange noises, the car has done over 110k miles ( it must of had a rebuild by now I would have thought) , but as I said the gauge didn't really move.also what should be the running temp be ?
Mines just been rebuilt at (an estimated) 130,000 miles ... why shouldn't it last that long?

Phil

andy43

9,548 posts

253 months

Sunday 23rd August 2015
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Also depends if it's a serp or preserp. And the oil it's got - Mobil one can be a bit thin, especially at that mileage. As long as it starts off at way over 30 psi when cold then sticks at roughly 30 when fans are on, and it rises with revs, and the fans cycle on and off ok with no actual overheating it should be ok. Maybe.

semaj

92 posts

125 months

Monday 24th August 2015
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Why do so many TVR owners think their cars have so many things to worry about? My 500 has 121k on the clock, has zero measurable oil loss between changes, is still on the original camshaft, never runs hot, does not shunt, shows 58psi oil cold at idle and 50psi hot, uses the cheapest 15/40 semi that I can find with the cheapest oil filters and 1litre of Lucas additive at each oil change. It goes like stink, returns 26 mpg touring and although I should not say this, has never let me down in any way. Some people worry if they have nothing to worry about I guess. Any vehicle is only as good as the last person to work on it in my opinion.

Lolo256

125 posts

69 months

Monday 2nd July 2018
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ClassiChimi said:
Fans should kick in at about 90 degrees.
If the engines been re built there should be evidence,,,, or assume it's done the milage recorded, it's not that unusual to get one doing that kind of milage but a 5.0 ?
Both temp and oil pressure gauges can give erratic readings so just let the engine idle until fans kick in and most importantly go off again and read the gauge at that point,,,, try and drive the car in traffic and keep listening for the fans to kick in/ out,,, when stopped I'd check top rad hose to see if it seems to be bulging etc. if the car drives and smells ok during a reasonable period,, say 20 mins and the temp and oil gauges are reading regular then it should be ok... At least on the water side !
Hi everybody!
When i bought my chim two month ago i checked that the oil pressure gauge was right (+readings). The gauge seems from the beggining to sometimes "bug" a little at zero but it disapeared each time soon. It seems it get worst and i changed the oil and filter but the readings was worst and worst.

I have almost everytime a near zero value going very few time under the zero (same as off!) Sometime at idle it get to 10-15lbs and then going back to zero when i put the throtle.

I wasnt very used to double check my oil pressure for some reasons so i drive with the car at zero inadvertingly, wich is for me proves that the oil pressure exists...i bought a new pressure sender but during this time do you think it s very risky to use the car? Are we ok the red light (it light up when key turned on) and a big boom should have happen if i had no pressure?

Ps : on this forum advices, my car going HELL better on low revs AND high revs.... LONG LIVE to this forum




Edited by Lolo256 on Monday 2nd July 23:12

Classic Chim

12,424 posts

148 months

Monday 2nd July 2018
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If the red light goes out as soon as the engine fires up then you should be ok.

If the pressure drops below 7 but some say 5psi the red light will activate.

In this warm weather I’d estimate many Tvr show very low pressure on the gauge once it’s hot.

The only way to put your mind at rest and actually find out is by using a mechanical oil pressure gauge to confirm its true pressure.

When I did this I recorded about 12 psi when engine was very warm at idle which soon went upto 50psi with added revs.
The gauge never read higher than 30psi even with a new pressure sender fitted and often read 5/10 psi at idle.
It’s actually more about flow rate than pressure as we have thinner oil than say 20/50 which shows lower pressure but more importantly should have higher flow which is what’s needed.




Lolo256

125 posts

69 months

Monday 2nd July 2018
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Classic Chim said:
If the red light goes out as soon as the engine fires up then you should be ok.

If the pressure drops below 7 but some say 5psi the red light will activate.

In this warm weather I’d estimate many Tvr show very low pressure on the gauge once it’s hot.

The only way to put your mind at rest and actually find out is by using a mechanical oil pressure gauge to confirm its true pressure.

When I did this I recorded about 12 psi when engine was very warm at idle which soon went upto 50psi with added revs.
The gauge never read higher than 30psi even with a new pressure sender fitted and often read 5/10 psi at idle.
It’s actually more about flow rate than pressure as we have thinner oil than say 20/50 which shows lower pressure but more importantly should have higher flow which is what’s needed.
Hi,
Thx to offer me some of your time!

It seems in your explaination that two factors could explain why the pressure is low ... my 300v 20w60 oil change + hot the wheather (35c+). Thx again!

Still strange that the gauge goes down with throtle and not the opposite... i saw that a bad ground would have a very different effect so i still suppose it s the electrical connection to the gauge or simply the sender hs or even the gauge herself...

N7GTX

7,823 posts

142 months

Monday 2nd July 2018
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I have a pre serp in another car and I ordered a new oil pressure sender unit as the reading on the gauge was very low - under 10 psi - but the oil pressure warning light did not come on. Fitted the new sender and the reading went up to around 45/50. Great I thought until I revved the engine up a bit. Then the gauge started going backwards down to zero. Sent the gauge back, got a new one and fitted it. Now it sits about 30 psi and goes up to around 45 when revved up a bit.
But......
After standing after a run so the engine is hot, when I next start the car the gauge shows between 10 and 15 psi. Once I have driven a few miles the reading goes back up slowly as the unit is cooled down by airflow.

So, the original gauge was faulty.
The first replacement was also faulty (going backwards like yours).
The second replacement is also faulty when hot.

They came from Rimmer Brothers and they have no markings on them so presumably made in China costing £24. The original is around £150. You get what you pay for.

Classic Chim

12,424 posts

148 months

Monday 2nd July 2018
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No,worries, I’ve had the gauge go down when accelerating ( very disconcerting )
It was nothing more than the female spade connector that goes onto the sender was loose. I just squeezed it with pliers until it made a tight connection.

Crank shells are sometimes shown to wear, 10/40 oil will show lower pressure but the flow to those bearings might well be greater than thick oil showing high pressure on the gauge.

The oil galleries are quite narrow and as we accelerate much faster than most RV8 derived cars you need that flow rate.
I add about 1litre of classic 20/50 motor oil to my 10/40 mix but only because I dont really accelerate abruptly and it helps with cold starts and cam train noise.
If I was doing trackdays I’d use Shell 10/40 semi synth RACING
this is the oil recommended by the engine builder and you can see why.

Before anyone starts changing the grade of oil they need to consider how they intend to drive the car. If it’s lazy Sunday drives which these cars are fabulous at then a thicker oil is no bad thing but start revving it and it’s a different story.

You can also loose hp and economy with thicker oils but it should help Cam life a little so a bit of a trade off between the two works for me.

The old RV can draw lots of unburnt fuel into the oil so it’s more important to change it regularly rather than get to hung up on expensive oils in my opinion smile


Lolo256

125 posts

69 months

Wednesday 4th July 2018
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N7GTX said:
I have a pre serp in another car and I ordered a new oil pressure sender unit as the reading on the gauge was very low - under 10 psi - but the oil pressure warning light did not come on. Fitted the new sender and the reading went up to around 45/50. Great I thought until I revved the engine up a bit. Then the gauge started going backwards down to zero. Sent the gauge back, got a new one and fitted it. Now it sits about 30 psi and goes up to around 45 when revved up a bit.
But......
After standing after a run so the engine is hot, when I next start the car the gauge shows between 10 and 15 psi. Once I have driven a few miles the reading goes back up slowly as the unit is cooled down by airflow.

So, the original gauge was faulty.
The first replacement was also faulty (going backwards like yours).
The second replacement is also faulty when hot.

They came from Rimmer Brothers and they have no markings on them so presumably made in China costing £24. The original is around £150. You get what you pay for.
Thx as usual! "Happy"to know that i m not alone with the reversed gauge! I also bought a cheap ebay sender we will see (i m a bit reluctant to put 60£ on a "not even sur it is" oem sender).


Lolo256

125 posts

69 months

Wednesday 4th July 2018
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Classic Chim said:
No,worries, I’ve had the gauge go down when accelerating ( very disconcerting )
It was nothing more than the female spade connector that goes onto the sender was loose. I just squeezed it with pliers until it made a tight connection.

Crank shells are sometimes shown to wear, 10/40 oil will show lower pressure but the flow to those bearings might well be greater than thick oil showing high pressure on the gauge.

The oil galleries are quite narrow and as we accelerate much faster than most RV8 derived cars you need that flow rate.
I add about 1litre of classic 20/50 motor oil to my 10/40 mix but only because I dont really accelerate abruptly and it helps with cold starts and cam train noise.
If I was doing trackdays I’d use Shell 10/40 semi synth RACING
this is the oil recommended by the engine builder and you can see why.

Before anyone starts changing the grade of oil they need to consider how they intend to drive the car. If it’s lazy Sunday drives which these cars are fabulous at then a thicker oil is no bad thing but start revving it and it’s a different story.

You can also loose hp and economy with thicker oils but it should help Cam life a little so a bit of a trade off between the two works for me.

The old RV can draw lots of unburnt fuel into the oil so it’s more important to change it regularly rather than get to hung up on expensive oils in my opinion smile

Hi,
Thx again! for the sender i ll take the advice and trying it before changing the sender.

Your advices concerning the oil change are a bit on top of both my english level and iq. Do you mean i m too thick with my 20w60? i saw a lot of person saying that "cat piss" is really bad for rv8 and that even 10w40 is not thick enough. I also saw that tuned 5.2 have 15w50. I ll not rev the car a lot because i know it not his cup of tea (5000max but most of time lesser) and that britishs need to be threated with care but i m clearly not soft at all and when then engine is hot i go wot!

Knows that yes i ll use expensive oil but not for longevity (300v isnt longlife at all it is to change each 3000miles even on the mouth of conceptors) but because this oil gave me the best power/fiability ever (less "washing" detergeant so maybe i dont bet right) ! You re the expert there...for you am i taking real risks by running so thick? Should i buy a can of 10w40 300v and fill the level each time i can? Or Should i change all the oil now?

Thx!!!

Classic Chim

12,424 posts

148 months

Thursday 5th July 2018
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Hi, I’m no expert sadly!
If Powers performance recommend 10/40 semi synthetic on rebuilt engines offering long warranties I’ll listen to them wink

If your engine runs ok and you don’t have any noise or cooling issues then it’s probably ok to leave it in there. I have no experience of the oil you mention.

These engines are very tolerant and originally used thicker oils so if your not revving it at High revs for long periods I can’t see how it will damage the engine.
Modern oils lubricate better regardless
My point was just about flow rate over pressure, clearly heavier oils will produce more pressure but that doesn’t automatically mean better lubrication and can cause less flow getting to the bearings but if the engines worn in so to speak then tolerances will likely be slightly bigger so thicker oils might well help to some extent.
But if this was the case then I’d expect the big engine builders to be using it but as far as I’m aware or at least Powers Performance still recommend 10/40

I decided to add more 20/50 on one oil change, I noticed it was slower and made more noise when starting up, that’s all about resistance and flow rate as the moment I thinned the oil by draining half of it away and adding more 10/40 it ran better and made less noise.

Personally if it’s changed every 3/4000 miles I doubt it makes any real difference but flow rate does concern me which is why I mentioned it. High revs and slow flow is very bad news for crank bearings. Most engine wear occurs before oil has heated up so using a thicker oil might be worse rather than better, just my humble opinion and something worth considering.