Help-Burning Oil
Discussion
I'd be interested in people's opinions and ideas on the following matter. I've posted this on General TVR Stuff and had little response, so thought I'd give it a go here.
During the winter my pre serp RV8 5.0litre Griff engine was rebuilt as it was using and burning an excessive amount of oil. During the rebuild it was found to have oval bores so required a small rebore and new long skirt pistons. The rebores ranging from just honing, to about 5thou. Each piston/bore was matched to each other. The engine also had a new cam and followers, timing chain and gears and a new oil pump. The heads were found to be fine and just required the valves re seating.
Since the build, the engine still uses alot of oil (1litre to 300 miles-ish) and kicks out a small cloud of smoke when under initial acceleration. On a journey, I can smell the burnt oil and it leaves an oily deposit on the rear end of the car.
The engine is due to come out again in a couple of months (don't want it off the road for the summer) to investgate and the people involved in the rebuild have a few theories as to why it's still using/burning oil. The engine was rebuild to the highest standards and the performance gained since the rebuild is excellent.
Any ideas people ?? It would be nice to find a nice simple answer to this problem although I doubt it will be the case.
Thanks in advance.
During the winter my pre serp RV8 5.0litre Griff engine was rebuilt as it was using and burning an excessive amount of oil. During the rebuild it was found to have oval bores so required a small rebore and new long skirt pistons. The rebores ranging from just honing, to about 5thou. Each piston/bore was matched to each other. The engine also had a new cam and followers, timing chain and gears and a new oil pump. The heads were found to be fine and just required the valves re seating.
Since the build, the engine still uses alot of oil (1litre to 300 miles-ish) and kicks out a small cloud of smoke when under initial acceleration. On a journey, I can smell the burnt oil and it leaves an oily deposit on the rear end of the car.
The engine is due to come out again in a couple of months (don't want it off the road for the summer) to investgate and the people involved in the rebuild have a few theories as to why it's still using/burning oil. The engine was rebuild to the highest standards and the performance gained since the rebuild is excellent.
Any ideas people ?? It would be nice to find a nice simple answer to this problem although I doubt it will be the case.
Thanks in advance.
Did you run it in nice and gently?
If the answer is yes then that is likely to be the problem.
As a youngster (a good many years ago) running in was a very gentle affair so that the rings could bed into the rough surface of the re-bore.
Todays rebore and hone produce a very fine finish by comparison and a gentle run in only serves to glaze the bores and the resultant high oil burn rate.
The experts on the Chevytalk forum advise breaking in the cam at 2000rpm for 20 minutes. Check for leaks etc., slam the hood and drive it hard up a hill.
My own Chevy engine build first ran on an engine dyno and the computer ran a 'break-in routine' which brought up the revs, loaded the engine with the dyno brake, then released it back to tickover. This was repeated for nearly half an hour.
During that day it went on to do a dozen full pulls and adjustments ending in 508HP.
Seems you need to treat them rough.
Steve
If the answer is yes then that is likely to be the problem.
As a youngster (a good many years ago) running in was a very gentle affair so that the rings could bed into the rough surface of the re-bore.
Todays rebore and hone produce a very fine finish by comparison and a gentle run in only serves to glaze the bores and the resultant high oil burn rate.
The experts on the Chevytalk forum advise breaking in the cam at 2000rpm for 20 minutes. Check for leaks etc., slam the hood and drive it hard up a hill.
My own Chevy engine build first ran on an engine dyno and the computer ran a 'break-in routine' which brought up the revs, loaded the engine with the dyno brake, then released it back to tickover. This was repeated for nearly half an hour.
During that day it went on to do a dozen full pulls and adjustments ending in 508HP.
Seems you need to treat them rough.
Steve
Well I didn't think I was too soft with it, the cam was bedded in for 20 mins at 2000RPM, then I drove the car using upto 3000RPM for the first 500 miles, changed the oil, then 4000 RPM but you're not the first to suggest this, so maybe I did run it in too gently. Maybe I should've took the approach I have with my company car and rag it from day 1 !! I was followed by a friend when it'd only done about 100 miles and he said there was visible smoke then, so could I have glazed the bores that soon ??
I'm going to fit an oil catch tank to the breather system this weekend to see how much oil is blowing through the breathers.
I'm going to fit an oil catch tank to the breather system this weekend to see how much oil is blowing through the breathers.
wixer said:
Mine is on the same oil. No problems with it. Not much help I know.
Has it been run in on it?
Maybe as a last resort before taking the engine out, it may be worth changing the oil to see if the rings may bed in finally.
Yep. And run in under strict instructions fron DJE who rebuilt the engine and the oil he uses as a norm I think. DJE in Nuneaton by the way.
Off the top of my head, first 500 miles below 2500revs, oil change. Then 1500 miles below 2500 revs and oil change. Then oil change at 3000 miles and take it up in stages. Don't quote me but have to check my build sheet for exact figures.
jmorgan said:
jmorgan said:
Mine is on the same oil. No problems with it. Not much help I know.
Has it been run in on it?
Maybe as a last resort before taking the engine out, it may be worth changing the oil to see if the rings may bed in finally.
Yep. And run in under strict instructions fron DJE who rebuilt the engine and the oil he uses as a norm I think. DJE in Nuneaton by the way.
Off the top of my head, first 500 miles below 2500revs, oil change. Then 1500 miles below 2500 revs and oil change. Then oil change at 3000 miles and take it up in stages. Don't quote me but have to check my build sheet for exact figures.
Mmm.. interesting. I know DJE, I live not too far away. Seems like you ran yours in easier than I did. A couple of friends have suggested the rebuild never cured the problem, as it was doing it before all the work was done. But exactly what still remains a mystery.
Thanks for the info. One last question, what is your oil consumption, if any ?
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff