Jeff Bowlsby

I have a 1981 4.5L...is it an interference engine? Which are the interference engines? Could not find this info from any other source.

whatudrivin

There are many threads on here about this. But you should not have an interference engine.

davek9

all 32v and hi compression euro 16v (300 hp) would be a good start

Lizard928

All 16V engines are non interference.
All 32V are interference.

This is true for stock in modified cars with no carbon build up.

davek9

Not true, I've see a bad WP and then a broken belt T Belt bend 4 valves on an 86 Euro 310 HP eng.

I know this has been debated here before, but I know what I've seen and helped fix.

Dave

James Bailey

the 10.4 /1 compression 310 hp Euro S 16 valve LH injection engines would seem to be the most likely to bend valves.

Also if the heads have been resurfaced shaved at some point in time or there is significant carbon build up it can be possible for some other 16 valve engines to bend valves.

Your 81 4.5 should have no problem......

Jeff Bowlsby

Excellent info...thanks for the responses guys. I am likeing this board.

Ian S4

Gates has a lookup function...
http://www.gates.com/part_locator/in...o=Interference

Lizard928

I've owned a 85 euro S 310bhp vehicle that I know the engine was all original on.
I put each cylinder to TDC then rotated the camshaft. There was no intereference. The factory manual backs this up.

17prospective buyer

By hand they probably aren't but with a fast spinning engine you have inertia come into play. I had my 32V S4 (stock) engine at points where it should have bent valves (by accident) and i don't think it did. Timed cams to 45 BTDC, forgot to move engine to #1 TDC compression stroke... You guys think fully drained/collapsed lifters would have something to do with this though? I cranked it through a full rotation with it timed to 45 instead of TDC and it spun just like normal, no resistance points. Perhaps the lifters offer enough cushion for no valve damage when hand cranking? This was just with a regular 1/2" drive ratchet. I think you'd deffinitely feel alot of resistance if you were bending a valve by cranking it over by hand.

depami

Way cool. Thanks for sharing.

123quattro

Doing it by hand with no oil pressure will let the lifters collapse some.

davek9

Yeah not meaning to disagree w/ you Colin as I know you are very knowledgeable, however I did feel a blanket statement about all 16v engines was pushing it a bit.

Dave

Lizard928

My statement was that all stock 928 16V motors are non interference.
The manual states this too.
However the tolerances are much smaller, and valve pockets can be the first place for carbon to build up. So even if you have a small amount of carbon build up it is possible to make the 310bhp euro 16V motors interference.

123Quattro,
The engine was run only a couple hours before. The loss would not have been enough to change the fact. When the car was restarted there was no lifter tick present. The amount of change which might have been lost would be negated by the thermal expansion of the aluminium block.

17 prospective,
The engine RPM has little to do with this. Either things touch or they dont. If the valve is lifting off the cam lobe then you will have other more noticeable problems. The only thing that the speed the engine is spinning will do is increase (with RPMs) the possible amount of damage that can happen if things DO touch. If they do not touch when stopped, they wont touch when spinning.

So to all, if you have a 16V engine which is stock, has never had the heads off, and you have no carbon build up, the engine is non interference. But if you have almost any carbon build up in the valve pockets on the pistons, then you likely have an interference motor. This can be viewed with a borescope pretty easily.

ROG100

As Gates says they are all interference I would not trust that part of the information they give.