Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[feeutfo]

I cleaned the plenum inside and out at the cambelt meet, and again last week, trying to solve a slight fume issue. now there is alot of wet/oily mess inside the plenum above the inlet duct to number 6. it is also blowing past the seals above and below the inlet base plate, again only on number 6.

Blowing past the seals in the plastic base plate.... Blowing past ? To where? Outside the inlet? That is your air leak if so?

[05omegav6]

pressure IN the inlet tract is forcing enough oil/fuel mix OUT past the seals on the base plate to make the seals wet. can text picture of near side head. surely a regular air leak on the inlet side would draw air into the manifold, seeing as the inlet manifold is relatively low pressure. :-/

[feeutfo]

pressure IN the inlet tract is forcing enough oil/fuel mix OUT past the seals on the base plate to make the seals wet. can text picture of near side head. surely a regular air leak on the inlet side would draw air into the manifold, seeing as the inlet manifold is relatively low pressure. :-/

If it's been sucking in air long enough would it run lean, and break the plug? Inlet manifold negative pressure is impressive.

Post the pic here...  Hang on I'll pm you.

[feeutfo]

Al's pics.

[Lazydocker]

Looking at that I'd say that the seal on the inlet isn't sound and that caused the cylinder to lean out to the point it destroyed the plug, then started blowing back up when the cylinder was flooded...

Of course, I'm no expert and I'm sure MDTM will be along soon

[05omegav6]

Thanks for that Chris

The inlet branch was  last disturbed at 100k,(now 162k), when I did the cam covers. Today is the first time that the inlet base has been removed since the engine was built.

Looking at that I'd say that the seal on the inlet isn't sound and that caused the cylinder to lean out to the point it destroyed the plug, then started blowing back up when the cylinder was flooded...

I think this might have happened the other way round :-/
It has been suggested that the plug may have failed as a result of being over tightened. Quite common on vx serviced Corsas apparently. The debris then damaging an exhaust valve, in turn leading to the blow back :-/

Either way net result is not good. :-/

[Lazydocker]

Thanks for that Chris

The inlet branch was  last disturbed at 100k,(now 162k), when I did the cam covers. Today is the first time that the inlet base has been removed since the engine was built.

Looking at that I'd say that the seal on the inlet isn't sound and that caused the cylinder to lean out to the point it destroyed the plug, then started blowing back up when the cylinder was flooded...

I think this might have happened the other way round :-/
It has been suggested that the plug may have failed as a result of being over tightened. Quite common on vx serviced Corsas apparently. The debris then damaging an exhaust valve, in turn leading to the blow back :-/

Either way net result is not good. :-/

Only way to know for certain about valve damage is the compression test

[05omegav6]

what figure should I be looking for with a compression test? ie what's normal/acceptable and how big does the difference need to be to signify a problem? :-/

Ta, Al.

[Lazydocker]

what figure should I be looking for with a compression test? ie what's normal/acceptable and how big does the difference need to be to signify a problem? :-/

Ta, Al.

First thing to look for is a dramatic drop on any cylinders from the others

[Kevin Wood]

what figure should I be looking for with a compression test? ie what's normal/acceptable and how big does the difference need to be to signify a problem? :-/

Ta, Al.

From memory probably 12-14 bar but, as said, we're looking for a significant drop on that cylinder alone, so do them all and compare.

Don't forget a teaspoon of oil in each bore if they are initially low.

Testing with the plenum removed is no problem provided that you prevent the fuel pump running(!) and keep anything loose away from the intakes.

Remove the 2 purple relays at the back of the ECU box to disable the fuel pump and ECU electrics.

Kevin

[05omegav6]

For reference: MAF unplugged, idle is reasonably steady at 900ish, Emissions light steady.

MAF plugged in, idle is approx 800rpm, and hunting very slightly, Emissions light flashing.

Strong smell of fumes, and number 6 very rattly in both cases.

[Marks DTM Calib]

Thanks for that Chris

The inlet branch was  last disturbed at 100k,(now 162k), when I did the cam covers. Today is the first time that the inlet base has been removed since the engine was built.

Looking at that I'd say that the seal on the inlet isn't sound and that caused the cylinder to lean out to the point it destroyed the plug, then started blowing back up when the cylinder was flooded...

I think this might have happened the other way round :-/
It has been suggested that the plug may have failed as a result of being over tightened. Quite common on vx serviced Corsas apparently. The debris then damaging an exhaust valve, in turn leading to the blow back :-/

Either way net result is not good. :-/

Not sure how that can cause significant blow back as yes, there is the possibility of the fresh fuel air mix coming into contact with hot exhaust gases via a leaky valve but, that would cause a hell of a pop in the inlet manifold every other stroke.

I should add that Mick Dundees car had gobbled some plug electrodes at some point and although there was scarring on the head, the valves were not affected.

Compression test is needed here I think.

The MAF results are a concern, when they get bad they do some very odd things including popping, over fueling the lot.

[05omegav6]

Right, just done compression test. :-/ results below, in bar:

1 10.2
2 10
3 11 (with oil, 8 before)
4 10
5 10
6 4 9.2 (dry)

Battery is flat, so been using a booster pack which died as I got to number 6, (should have started with that one ), so not convinced about that result.

All 6 plugs were wet. Engine has only been run for a minute or so since Thursday.

Will post second result for 6 once the booster is re charged.

Al.

[05omegav6]

The MAF results are a concern, when they get bad they do some very odd things including popping, over fueling the lot.

Also having read Oti's thread, are v6 MAFs interchangable?
Thinking 2nd hand as a short term test. :-/

[feeutfo]

The MAF results are a concern, when they get bad they do some very odd things including popping, over fueling the lot.

Also having read Oti's thread, are v6 MAFs interchangable?
Thinking 2nd hand as a short term test. :-/

2.6 and 3.2 maf's are the same, search the Bosch part no. On the maf itself. Also used on transit vans among others. Pre face lift are differant.