M20 Oil Contamination / Consumption

[SilverShadow]

Guys first of all thank you for your help on this thread - its much appreciated and owe you big time.

I got a little busy at the end of last week and didn't get a chance to work on the car.

I know we have been through this before and the motor has been rebuilt since but are you 100% sure there are no air leaks from the manifold?

To be 100% are we referring to the inlet manifold? All the gaskets were changed during the build, however I've one of the bolts that hold the vac pipe connection flange seems loose due to the thread being worn (forever spinning).

Did we do the fuel filter last time round? I have seen E30s running about with low fuel pressure and the original 1980s filter still fitted! Just a little bit blocked up!

Nope since the recent builds the fuel filter hasn't been changed. I have changed it in the past but will look to get this replaced with a new one.

Edit to add - Could this just be a read herring? It should go up with WOT and load.
But we are talking about snapping the throttle on an engine with no load, resulting in a very high rate of acceleration of the engine, will this give the same expected result even with the short duration the throttle can be opened before hitting the rev limiter.

Yes - when I tested the pressure i had blipped the throttle during idle.

Also just looked back for the other thread and found you have tried another ECU since I last looked at it, with no real change to the amount of smoking even though it was a stock 325 ECU.
So we can forget that at least for now.

Yes I did swap it out for a stock 325i ecu previously however i still ran the engine with the contaminated oil (thinned by the fuel and passing by the rings and burning). My theory now is to do a oil change and drop the current mineral oil that I've used to break in the rings. Use fresh 15/40 semi/oil filter and swap the ECU using a chip dedicated to a 2.7 engine from Speadtouch and check the oil contamination again after so many miles??

How does the above approach sound, any feedback on the would be appreciated.

[SilverShadow]

General question to all in this thread - If a jack had found its way onto the fuel lines and pinched/partially blocked the feed and return could this explain the high pressure at idle and restricted/low pressure when revved?

Forgot to mention that I'm going to try and get the car up on the rump and inspect the fuel lines this weekend.

[HairyScreech]

Any joy?

[SilverShadow]

Any joy?

Sorry for the late reply on this, been away for work.

Got some good news and some bad news.

I'll start with the good; Changed the ECU with a 2.7 chip from Speedtouch, dropped the oil, new oil filter and some 15/40 semi. I also changed the fuel filter and inspected the fuel lines through from the tank to the engine bay. The lines are all in good nick and there's no damage to them.

Now for the bad, the engine has continued to smoke and consume oil even with the new ecu setup and new oil. I haven't done a contamination test as I've only done approx 70miles with the new oil.

I later inspected the throttle body and rubber intake boot and was full of oil (see below). This oil has accumulated from the recent rebuild around 700miles ago!





I know this caused by crank case ventilation due to rings/bores. Could it be early days to suspect anything as the rings could be still seating??

I later inspected the plugs which seem to be ok (plugs 5 and 6 missing from pic but were in similar state)



So... whats the verdict on the latest? Its looking a bit grim and suspecting bores and thinking to add a oil catch can on the rocker to TB breather pipe?

However my next plan of action is that I have cleaned the TB and rubber boot and will monitor and recheck.

As a side note when i had cleaned out the TB etc the engine was running so nice and started with no issues. But recently seems that its struggling to start and back firing - once started and warmed up its fine with no running issues.

Any feedback would be much appreciated.

[reggid]

those plugs look oil fouled not suprisingly

[k]

I assume that all the piston rings are in the right way up?, just a thought on what is a very interesting thread but nightmare for the owner

[Brianmoooore]

Definitely oil fouled plugs, and there still remains the unexplained fuel pressure behaviour.

[SilverShadow]

Another update”¦

After cleaning the TB, rubber boot and ICV and driving less than 100miles I noticed that the engine has gradually become difficult to start (back firing, popping), sluggish, smoking etc.

This weekend I inspected the TB, ICV, rubber boot, AFM and again came across oil that has been accumulated within a short period of time (doing less than 100miles).







I'm quite surprised in how much oil had come through...

Upon cleaning the parts and can see a drastic change whereby the engine starts on first turn of the key, no back fire, smoke, generally running much better etc.

For now I have concluded to opt in for a oil catch can to help prevent oil build up in the intake system. I know this is not the "fix" for the problem but it would allow the engine to continue to bed in (rings) and avoid the above issues as mentioned while in use. I'm just hoping the bores aren't mallard!

I am planning to do another oil contamination test in the next 100 miles and recheck results.

What peoples thoughts on this so far and the idea of the catch can??

[DanThe]

Whats the underside of the cam cover like? Does it have a flat plate riveted to it?

[SilverShadow]

Whats the underside of the cam cover like? Does it have a flat plate riveted to it?

Thats correct.

Few years back when I had it powder coated it was cleaned for old oil whilst plate in situ.

[Carmo13]

Just a thought,
Is the rocker cover breather pipe clear and unrestricted?
If this was blocked, could it lead to a build up of pressure, resulting in oil in the intake system?

[k]

That's a lot of oil in the intake system, only way in is via engine breather from valve cover to inlet manifold.
Disconnect it and see what the crankcase is blowing out

[HairyScreech]

Blow by was ok when it was leakdown tested.

A catch can may be able to give you enough clear/good running time to find the problem.
If it was plumbed into the breather pipe and done to allow oil to drip down back into the crank case via the dip stick or oil return pipe then it would prevent the inlet filling with oil.
Perhaps more of an oil separator rather than a catch can.
As you say no fix but maybe enough of a band aid to work out what the hell is going on with this engine.

How is the overfueling/fuel smell with the ECU/chip changed?

If you clean the oil out of the inlet and get it warm whats the fuel smell like then?

[SilverShadow]

Blow by was ok when it was leakdown tested.

A catch can may be able to give you enough clear/good running time to find the problem.
If it was plumbed into the breather pipe and done to allow oil to drip down back into the crank case via the dip stick or oil return pipe then it would prevent the inlet filling with oil.
Perhaps more of an oil separator rather than a catch can.
As you say no fix but maybe enough of a band aid to work out what the hell is going on with this engine.

How is the overfueling/fuel smell with the ECU/chip changed?

If you clean the oil out of the inlet and get it warm whats the fuel smell like then?

Thanks for the reply.

Yes - the leak down test was showing max 10% leakage prior to the recent change of rings. With the recent build taking place the compression was all around the 190/200psi.

I already placed an order for a catch can which turned up today. So I'm looking at where/how to plump it in - the unit will be plumbed in between the rocker breather hose to the throttle body. Its a catch can which will need to be emptied every so often but will help me identify what is going on.

I still need to do another oil contamination test since changing the ecu/chip - hoping to get this done over the weekend.

On a side note I ordered a cheap bore scope/endoscope unit from ebay. Planning to take pics of each of the cylinders this week to see the condition of the bores and pistons. Will load the pics up for review.