Heavy oil consumption

el chapo · Post by **el chapo** » Sat May 10, 2014 2:33 pm

Hello, I was wondering if anyone might have any ideas as to why my engine has started burning large amounts of oil.

The engine was built from a 4.0 block which I then put 4.6 pistons and crank into. The injection system is a 3.9 hotwire with a 4.6 "chip", the front cover etc is from a 3.5.

I managed to cover 100 -150 miles without any major smoke or oil consumption but after this oil usage was quite extreme, oil level going from the top of safe to below the low level in less than 40 miles. This was accompanied by large clouds of smoke which only get worse the more I rev the engine.

Removal of the spark plugs revealed oil to some extent on all but 2 of the plugs. A couple were so badly caked with burnt oil that the engine was misfiring.

I removed a head to see if there was anything obvious, and there was some oil in the inlet ports. valve stem seal look OK though.

Removed a piston on the worst effected cylinder and checked ring gaps which were above tolerances but not vastly.

Put everything back together to carry out a compression test and all cylinders between 160-180psi nut the engine is still smoking noticeably.

The dipstick is the original from the 4.0 engine but the sump is a 3.5 with some bashing to allow for the crank stroke. Is this the correct dipstick for a 4.6 ?

Any ideas would be much appreciated.

unstable load · Post by **unstable load** » Sat May 10, 2014 3:45 pm

Is your crank case ventilation clear of blockages?

ChrisJC · Post by **ChrisJC** » Sat May 10, 2014 4:38 pm

4.0 / 4.6 dipsticks are the same.

Have you any idea how much oil is in the sump? I guess at that rate of consumption you could quickly drive until it drops of the bottom of the dipstick and see if it's still smoking!

Is the breather system full of oil? What happens if you remove the breather from the inlet and plug the inlet? Does it stop smoking, but p*ss oil fumes from the breather?

Chris.

kokkolanpoika · Post by **kokkolanpoika** » Sat May 10, 2014 6:56 pm

4.0/4.6 dipstick is different than 3.5l dipstick..
Your oil level will sit too low if you use 4.0/4.6 dipstick with 3.5litre sump, approximately 1litre if use SD1 sump.. Don´t remeber how mutch if use Classic range rover sump..
I make those measurements approx 3month ago..

Do you use original piston rings or some britpart/bearmach? My dad buil approx 20years go 3.5 litre engine with new pistons/rings.. First 1000km it is ok, then it will start to eat oil approx 1l/100km..
So he change original rings without hone, and engine is still running some off road car without oil consumption..

Ian Anderson · Post by **Ian Anderson** » Sat May 10, 2014 9:04 pm

From empty to full how much oil do you add to your sump at an oil change.

Do you have a scraper system or I'd the larger throw crank foaming up the oil.

Enough for it to then get sucked out the top of the engine into the plenum?

Ian

el chapo · Post by **el chapo** » Sun May 11, 2014 8:23 am

Thanks for the quick replies.

The breather pipe running from the drivers side rocker cover to the plenum appears to be clean at the plenum end but maybe a little oily at the rocker end. I have disconnected this pipe from the plenum/throttle body and it still seems to be smoking, but havent noticed any fumes from the breather.

I'm afraid I don't know how much oil I put in the sump.
I compared the 4.0 dipstick with my old 3.5 and it appears to have the same mid point between high and low but the 4.0 has a smaller range.
Using the 3.5 sump and oil pick up pipe/strainer could be causing a problem?

I'm not really sure what a scraper system is, would foaming up the oil go up through the piston rings or out through the breather ?

When I built the engine up, I used the piston rings that were already fitted to the second hand 4.6 pistons. Probably not the best idea !
The rings on the 4.6 pistons have no markings unlike the 4.0 pistons which has AE rings.
I am worried that the 4.6 pistons and rings could be worn, but I'm still slightly surprised that the engine did not smoke from the start and the compression test looked OK?

ChrisJC · Post by **ChrisJC** » Sun May 11, 2014 10:57 am

I doubt if the oil level is causing a problem. I suppose to be sure you could get a dipstick / tube that goes with your sump. For reference, I have a Range Rover classic sump and dipstick on my 4.6 block, no problems at all.

Chris.

kokkolanpoika · Post by **kokkolanpoika** » Sun May 11, 2014 1:21 pm

You cannot compare only dipstick, you have to compare also dipstick tube.. Those have got small difference in lenght..
I have to cut approx 10-15mm of the top for 4.6 dipstick that oil level will sit same level as original 3.5 dipstick and SD1 sump..

I don´t think that oil level is a problem..

RoverP6B · Post by **RoverP6B** » Sun May 11, 2014 7:31 pm

Using the 3.5 litre sump with the 4.6 engine is fine, but as has been mentioned, you must use both the 3.5 dipstick that matches the sump, and the matching dip stick tube.

There are different 3.5 litre sumps, so you need to find the matching parts for THAT particular design of sump.

I use a 3.5 litre P6B sump, dip stick tube and oil pick up on my 4.6 litre engine, and have experienced no problems at all in over 100,000 Miles of use since installation in 2007.

Ron.

el chapo · Post by **el chapo** » Sun May 11, 2014 8:16 pm

I will see if I can find the old dipstick and tube but at the time I think it was compared using the tube as well.

Is it possible for oil to make its way up to the inlet port from the cylinders ?
The ports looked otherwise clean except for a small amount of what looks like engine oil sitting on top of the valves, more in some ports than others.

el chapo · Post by **el chapo** » Tue May 13, 2014 9:40 pm

It looks like changing the piston rings is probably my best option.
Does anyone have any recommendations on where to get rings or are OEM the best bet ?

what are the tolerances if I were to get the pistons and bores measured?

Would 4.0 pistons on 4.6 crank and rods give a compression ratio too high for normal petrol ?

sassanach · Post by **sassanach** » Wed May 14, 2014 11:45 am

i have a 4.6 "thor" lump which had exactly the same issues as yours,perfect compression etc.turned out that the oil control rings were so worn that you didn't need a ring compressor to reassemble them back into the block.

el chapo · Post by **el chapo** » Wed May 14, 2014 1:04 pm

Thanks for that, it does sounds similar as the oil rings in mine would almost fall down the bore when testing the gaps. I Just didn't know how tight they were suppose to be. Thanks again.

DaveEFI · Post by **DaveEFI** » Wed May 14, 2014 1:39 pm

Personally, I'd never use 'secondhand' rings . They tend to bed in to the individual bore. A secondhand piston in good condition of the correct size is a different matter.

el chapo · Post by **el chapo** » Tue May 20, 2014 11:14 am

I have started taking the engine apart to fit new piston rings and on removal of the intake manifold I have found plenty of blackish engine oil all over the inlet ports and even up the intake manifold.

Is it possible for engine oil to get into the inlet ports and intake manifold as a result of the piston rings ? The rocker breather has not been connected to the plenum chamber or throttle body at all, so the oil can not be coming from there.

Thanks, James