smoke on over run :-(

ged · Post by **ged** » Sun Dec 06, 2009 7:39 pm

Hi Tony,

Is the smoke blue-grey & if you've got the window down do you get a whiff of engine oil? I think from memory brake fluid burns white & smells different.
I had a similar problem with my 4.6 on the overrun after about 1000 miles. It turned out to be crap valve stem seals. Two of them had popped off. I bought another set from real steel & after fitting them all was well.

Post by **Coops** » Sun Dec 06, 2009 7:40 pm

no fluid leaks,
all baffle plates in place,

have refitted the 3.9 breather setup complete with the T piece,
im still getting a bit of smoke but no where near as bad as it was, just get a little wisp when nearly at a stop,
you get a puff of smoke out the exhaust when you pull away after stopping after doing the above to,

otherwise no other signs of smoke, when driving normaly etc as stated before,
im going to be removing the rocker covers over crimbo to make sure all stem seals are still in place,
thanks for the tips etc so far,
at least the engine is getting some upper end lubrication

Post by **Coops** » Sun Dec 06, 2009 7:42 pm

also,
when stationery if you rev her quite hard as in blipping the throttle you sometimes get a slight puff of oil smoke then too.

Post by **Coops** » Sun Dec 06, 2009 7:49 pm

ged wrote:Hi Tony,

Is the smoke blue-grey & if you've got the window down do you get a whiff of engine oil? I think from memory brake fluid burns white & smells different.
I had a similar problem with my 4.6 on the overrun after about 1000 miles. It turned out to be crap valve stem seals. Two of them had popped off. I bought another set from real steel & after fitting them all was well.

hi ged yeah it does smell of oil,
its a pain as i also have an oil leak that dont help as that is giving off a bit of smoke too,

i will check the stem seals when the rocker covers are off over crimbo, thanks mate.

RoverP6B · Post by **RoverP6B** » Sun Dec 06, 2009 8:18 pm

Yes indeed, burning brake fluid will produce lots of white smoke but apart from that oil being drawn in via the breathers sounds the most plausible.

Ron.

Darkspeed · Post by **Darkspeed** » Sun Dec 06, 2009 9:03 pm

Had this on an old Alfa I had but happened when cornering. The fluid level in the servo leaking past the seals met with the vacuum take off and then it was instant fog maker - However its a completely different kind of smoke to overrun oil smoke as its a white fog and not blue haze.

Only time I have ever had oil smoke on overrun was when something was worn out !!!

Ian Anderson wrote:Have you checked your brake fluid level?

I remember you working aload on the vac booster

If the seals don't work it is possible to get brake fluid drawn past the seals and then sucked into the plenum and burnt - of sourse this would happen at the highest vacuum - ie massive overrun

Ian

ged · Post by **ged** » Sun Dec 06, 2009 9:43 pm

Hi again Tony,

Just a quick check to prove or disprove the breather theory. Disconnect the hose at the manifold or plenum (where ever you have it connected) & run your finger inside. If it's oily I'd say you were getting over oiling on the top end or your rings haven't bedded in properly yet. Take it for a quick blast with the breather disconnected & your vacuum plugged, if you still get smoke at least you can discount the breather system sucking oil into the inlet tract.

Hope this helps

Post by **Coops** » Sun Dec 06, 2009 9:46 pm

mmmm i wonder if the rings are not bedded in right yet,
how long does that take usually?

JP. · Post by **JP.** » Mon Dec 07, 2009 5:10 pm

thev8kid wrote:mmmm i wonder if the rings are not bedded in right yet,
how long does that take usually?

Normaly three times up & down the street.
If they are not bedded in after 300 miles you'll have glazed walls meaning a problem by now.
Easy to check......compression test.

Post by **Coops** » Mon Dec 07, 2009 5:17 pm

will try and do a comp test the week end mate,

also im going to go back to using 20w50 oil instead of the 15w40 im using now in this new engine.

ramon alban · Post by **ramon alban** » Mon Dec 07, 2009 11:35 pm

How do you plan to overcome possible excess vacuum?

ppyvabw · Post by **ppyvabw** » Tue Dec 08, 2009 3:17 am

With respect, are you possibly in some deep seated state of denial here. I hate to say it but could it not be a busted ring? Or possibly an over heated ring that has lost it's hardness and gone for a poop and not bedded in?

Post by **Coops** » Tue Dec 08, 2009 5:49 am

ramon alban wrote:How do you plan to overcome possible excess vacuum?

as im using a mapped system with no AF i need the stepper to control idle and cold start idle,
the breather and vacuum setup is as per the old 3.9 system where i had no problems what so ever,
if this is wrong why did the 3.9 behave itself? and why did rover use this setup?
failing that not sure how to control it,
regarding the rings, anything is possible with this fekin car at the mo,

ChrisJC · Post by **ChrisJC** » Tue Dec 08, 2009 8:21 am

ramon alban wrote:How do you plan to overcome possible excess vacuum?

Not sure what you mean by excess vac? My 4.6 runs to about 30inches of mercury on overrun (total vacuum is only 32 I think), which is pretty good.

I don't have an issue with blue smoke.

Chris.

ramon alban · Post by **ramon alban** » Tue Dec 08, 2009 9:01 am

ChrisJC wrote:
ramon alban wrote:How do you plan to overcome possible excess vacuum?
Not sure what you mean by excess vac? My 4.6 runs to about 30inches of mercury on overrun (total vacuum is only 32 I think), which is pretty good.

I don't have an issue with blue smoke.

Hello Chris,

I was really only addressing Tony's earlier question when he queried if an excess vacuum caused by him removing the original TP overrun valve could be the source of the problem, and of course it could, because the original valve now removed, had the effect of "dumping" excess vacuum.

As it seems now, there may ALSO be a mechanical breakage too.

My full analysis of the original overrun valve makes an interesting read as to how the system behaves - without a method of vacuum limitation