28 replies to this topic

[blacktulip]

the bores and pistons may be fine and it might be the guides,valves or both in the head causing the problems.

[gazza82]

Was the head and block deck checked for "flatness"?

[westlin]

Ive not had the block apart, so not measured anything, engine is as it was bought. So the question is, do I give it some beans and let the rings bed in, check the head gasket, or the valve guides.

yours scratching head!!!!

[Cooperman]

They are all a bit low generally, with the centre two especially so.

What was the compression ratio set to?

It won't be valve guides as they have no bearing on compression figures.

It might be rings not bedded in, or something more serious.

[fwdracer]

Do another 200-250 miles and check the compression again-expect to see an equalisation across the cylinders and increase in psi (150-160) as well as reduction in visible oil smoke as the rings 'bed-in'.

 

Does the car only smoke when the car has been idling or when you accelerate after being on closed throttle/on overrun? This would indicate worn guides (oil being drawn down them) and has very little to do with low cylinder readings you have currently.

 

Go and run the car, short local loops so you aren't too far from home. If the motor goes off song or shows any sign of overheating, get the car off the road asap. Whip the head off and inspect the bores. A good quality hone will still show oil retention cross hatch all around the cylinder bore. If the head gasket was new when the engine was built I can't see how it would have failed between 2-3 with just sixty miles on the clock. Unless it was duffer (There was batch of suspect BK450's around 12-18months ago). Personally I'd use copper H/gasket but it again is down to preference.

Edited by fwdracer, 22 December 2014 - 06:12 PM.

[westlin]

Ok will see how it goes, a few oil leaks to work on over Christmas and will get some miles on it.

Thanks all

[westlin]

Guys, have run the car for about 350 miles. Re did the compression test and no great change. I also changed the oil to 10w 40. The following day found mayo under the oil cap. Cleaned and ran again and still more mayo, which points at a head gasket.

Ive just stripped the head and im even more confused. Head gasket looks ok, but head and pistons have a tar like coating. Pictures attached. Ive out a steel rule across the block and head and appear flat.

Help!!!!!

Attached Files

•  Head gasket.jpg   195.02K   19 downloads
•  Pistons.jpg   228.58K   28 downloads
•  Head.jpg   240.91K   16 downloads

[carbon]

Now you have the head off you can check all of the valve stems and guides for wear, and replace all the valve guide seals.

 

How many miles has this engine done since the build?

 

And are the traces of liquid in the piston dishes oil, or water from when the head was taken off?

[westlin]

Im going to replace the stem seals regardless, fluid is only in the dishes. Looking at the gasket it looks like there is an element missing between 2 and 3 which could explain the ingress. The question is do I get the head re skimed regardless?

Since it was rebuilt it done about 500 miles.

Any thoughts?

[sonikk4]

If the head is true then no need to skim. Do use a good quality gasket though. 

[westlin]

I have a bk450. Going to give the head a good clean tomorrow and check with my steel rule.

Ill keep you posted

[carbon]

While you have the head off would suggest also do following :

- check and note type of piston fitted, find out piston dish capacity in cc

- check top of piston to block deck clearance, how far down the bore are they at tdc

- check depth of head, should be 2.75 inch unskimmed

- check head chamber volumes if possible.

 

With this info you should be able to work out static compression ratio of the motor.

[westlin]

Head has now been skimmed , 6 thou taken off. Replaced the stem seals and replaced the exhaust valves as all the seats were badly pitted.

ive taken the measuresments, so how do I work out the compression ratio. Head chamber I dont know how to measure.

thanks

[westlin]

Engine is working a whole lot better but now have an annoying oil leak. It looks like it is spraying from between the head and the block. Cleaned the engine bay and fitted a new breather pipe. After running found a band of oil on the pipe about the height of the join in the block. I'm going to reckeck the head bolts. But any other suggestions. Can I use a gasket sealant as well.

Thanks in advance