Rover V8 oil pressure
Discussion
Buddy's got a RV8 in a kitcar and the oil pressure's playing up. When it gets nicely hot on tick over the oil pressure drops off to 5psi and the top end sounds like a bag of spanners. Give it a few revs and it's OK, but on tickover it's really not nice.
He fitted a new oil pump last year on the advice of a local "expert" but not much difference. Not sure if he pre-loaded the new oil pump with vaseline as I believe you're supposed to but since he gets decent pressure once the revs build up I guess that's not a problem now.
Anyone any ideas?
He fitted a new oil pump last year on the advice of a local "expert" but not much difference. Not sure if he pre-loaded the new oil pump with vaseline as I believe you're supposed to but since he gets decent pressure once the revs build up I guess that's not a problem now.
Anyone any ideas?
100SRV said:
Slade Alive said:
Check the spring in the oil pressure release valve. Common problem.
Also check that the plunger for oil pressure relief is able to moove freely, it is not unusual for the plunger to become scored and stick open thus relieving the pressure permanently!What oil is he using?
The Rover V8 is old technology & they aren't overly fond of modern thin synthetics. Common issue with Land Rovers & RRC & a change to a 20/50 can make a significant diference.
That said if the engine is high mileage (that's anything over around 70k) the cam & its followers are likely worn out.
Might find this of interest: http://www.v8engines.com/engine-4.htm
The Rover V8 is old technology & they aren't overly fond of modern thin synthetics. Common issue with Land Rovers & RRC & a change to a 20/50 can make a significant diference.
That said if the engine is high mileage (that's anything over around 70k) the cam & its followers are likely worn out.
Might find this of interest: http://www.v8engines.com/engine-4.htm
http://www.upmpg.com/tech_articles/motoroil_viscos...
"I can't tell you how many times I have heard someone, usually an auto mechanic, say that they wouldn't use a 5W-30 motor oil because it is, "Too thin." Then they may use a 10W-30 or SAE 30 motor oil. At engine operating temperatures these oils are the same. The only time the 5W-30 oil is "thin" is at cold start up conditions where you need it to be "thin."
"I can't tell you how many times I have heard someone, usually an auto mechanic, say that they wouldn't use a 5W-30 motor oil because it is, "Too thin." Then they may use a 10W-30 or SAE 30 motor oil. At engine operating temperatures these oils are the same. The only time the 5W-30 oil is "thin" is at cold start up conditions where you need it to be "thin."
MattYorke said:
http://www.upmpg.com/tech_articles/motoroil_viscos...
"I can't tell you how many times I have heard someone, usually an auto mechanic, say that they wouldn't use a 5W-30 motor oil because it is, "Too thin." Then they may use a 10W-30 or SAE 30 motor oil. At engine operating temperatures these oils are the same. The only time the 5W-30 oil is "thin" is at cold start up conditions where you need it to be "thin."
I find this misleading. The way you explain suggests they're referring to normal engine operating temps, yet the choice appears to be around the cold operating temps if as you say 'they' chose 10W or straight 30 over a 5W. So maybe these auto mechanics were wanting a thicker grade at cold start up and not at fully warm? It's not clear from your words why you assume 'they' are referring to the 30 and not the W rating?"I can't tell you how many times I have heard someone, usually an auto mechanic, say that they wouldn't use a 5W-30 motor oil because it is, "Too thin." Then they may use a 10W-30 or SAE 30 motor oil. At engine operating temperatures these oils are the same. The only time the 5W-30 oil is "thin" is at cold start up conditions where you need it to be "thin."
I'd have trouble believing a mechanic wouldn't know oil viscosity and how to read it off the carton or bottle not knowing the difference between the first part of the number over the second, or not knowing the difference between a 30 or 40 or 50 weight oil in viscosity terms. Surely not?
They're not my words - I cut & pasted them.
But the point is valid - why would you want an oil that's like treacle when cold, when you could have it much closer to its hot viscosity, which is actually what the motor wants. ie why would you ever choose a 20W50 over a 5W50, for example? I don't think you would, except in some very special cases, such as to bed the rings in with a mineral oil (20w50 being more typically a mineral).
But the point is valid - why would you want an oil that's like treacle when cold, when you could have it much closer to its hot viscosity, which is actually what the motor wants. ie why would you ever choose a 20W50 over a 5W50, for example? I don't think you would, except in some very special cases, such as to bed the rings in with a mineral oil (20w50 being more typically a mineral).
If you look through RRC workshop manuals fluids spec section you will find a very wide range of oils that can be used.
That said, the LR handbook for mine - 1986 3.5EFi - only shows 15w40 recommended in the 'forecourt data' section. Even though it too lists many different types as being OK to use.
You may find on higher milage RV8s that thin synthetics will give you a very rattly top end at initial start-up until the pump has got enough oil to the followers which rely on being filled with oil.
That said, the LR handbook for mine - 1986 3.5EFi - only shows 15w40 recommended in the 'forecourt data' section. Even though it too lists many different types as being OK to use.
You may find on higher milage RV8s that thin synthetics will give you a very rattly top end at initial start-up until the pump has got enough oil to the followers which rely on being filled with oil.
Edited by paintman on Tuesday 12th July 21:02
Well Matt 20W isn't really like treacle when cold. Nor is a straight 50 or 60 weight come to it. But I see what your point. And whilst I am no expert and oil debates can go on forever when they really shouldn't, I am more alarmed your comment suggests there are mechanics out there with little to no understanding of oil indexing. Surely some basic knowledge exists amongst all taught mechanics? I would like to think so.
As for say 20W-50. A 20W will at cold temps and cold clearance give protection against being squeezed similar to the protection offered by 50 at normal running temps and clearance. Or in other words, no 20W, just 50, will not offer at cold clearance the protection against being squeezed a 20W will. Or something like that. HTH.
As for say 20W-50. A 20W will at cold temps and cold clearance give protection against being squeezed similar to the protection offered by 50 at normal running temps and clearance. Or in other words, no 20W, just 50, will not offer at cold clearance the protection against being squeezed a 20W will. Or something like that. HTH.
paintman said:
You may find on higher milage RV8s that thin synthetics will give you a very rattly top end at initial start-up until the pump has got enough oil to the followers which rely on being filled with oil.
Do you *really* think that these followers empty of oil when the motor is stopped? Ever tried to evacuate the oil from one without taking apart? Even if this did happen, which it doesn't to any appreciable degree, the 5w variant would re-fill far quicker than the 15w or 20wHappily on 5w50 synthetic here; give me the cold start protection every time. The only possible deficiency against a 15w50 or 20w50 is that the 5w50 will be less chemically stable than the others but I doubt a 2v pushrod motor will ever really stress it, especially given the short oil change intervals typically used.
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff