Interference engines or not?

[c_lee]

I was certain that the B200E was a non interference engine from research I did years ago but I have had a PM raising doubts in my mind.

It has been mentioned that 244's / 240's with a silver top are non interference and ones with a black top are interference.

Does anyone have a definitive list of which engines are interference and which ones aren't.

Thanks - Colin

[Paul240480]

Just been searching around the forums & found this in the 700/900 section which I have copied:


Do I Have an Interference Engine? [Editor] An "interference" engine is one in which the tops of the pistons and the valves may collide if the timing belt breaks or is misaligned. If you have an interference engine, you MUST change your timing belt on schedule or else you risk very expensive damage. You must also pay closer attention to the condition of the tensioners, pulley bolts, and front seals: anything that can cause the belt to fail prematurely must be repaired quickly. Not all Volvo engines are non-interference. [Colin Shepherd/Peter Milnes]
"Interference" Engines:
B200 series (including E, F, G, FT, GT)
B230E (high-compression B230 sold outside of North America)
B204 series (including E, F, FT, GT)
B234 series (including F, G)
All B5XXX five-cylinder inline engines and 6XXX six-cylinder engines
The B230 series is non-interference with the exception of the B230E.
FK is also a non interferece engine,
Edit : 700/900 FAQ paste

[jmz]

so from that, do i read that my 2.3 carbed engine is non-interference yet the 230e (injection??) is interference?

[Michael J]

Originally Posted by Paul240480

...
The B230 series is non-interference with the exception of the B230E.
...
Edit : 700/900 FAQ paste

I'm going to reach for my pillar of salt for this one. There is a fundamental disagreement here with the Haynes Book of Lies for 240 Series 1974-1993, which says that the B230 is an interference design, unlike B21/B23.

[Clifford Pope]

Never believe anything anyone tells you about interference/non-interference.
Even if a particular model is said to be non-interference, it can be affected by previous head-skimming.

The only way to be certain is next time you change the timing belt, set the camshaft so that a valve is on maximum opening, and then VERY CAREFULLY turn the crank by hand with the plugs out to see whether the piston touches the valve.

After that you will KNOW whereas everyone else will be guessing.

[Clifford Pope]

I have read that it is also possible for an engine to be sometimes interference - ie if the cam happens to stop in a particular position when the belt breaks, then you might just be lucky. But probably only once!

[S40T3]

I'd be tempted to put the crank on TDC and turn the cam sprocket with a spanner as I reckon this would be less likely to bend as valve - but I could be wrong!

[Michael J]

I think it would be better to turn the crank. With no belt, the spark plugs removed, and the gearbox in neutral, it ought to turn quite easily by hand and making contact ought to be obvious.

[Clifford Pope]

That was my thinking. As when setting timing, with the plugs out you can inch it backwards and forwards just by grasping the pulley. The camshaft is hard to turn because of compressing the valve springs, and it goes in a series of jerks as each cam bounces over the balance point.

[rustytoba]

Having done a bit of work as a lad on my brothers 360's, B200 (E and K) I remember them having chambered cylinderheads and flatish piston crowns so normally termed interferance heads, as piston crown at TDC and valves fully open would mean curtains!!!!

I think some post 85 B230's (not sure what sufix) had a 'Heron' head fitted, these are a near flat cylinderhead design and have recessed pistons to accomodate the valves, this design could be considerd non-interferance, as the piston crown at TDC and the valves fully opened there would be no collision.

However I am unsure how to ID these 'Heron' heads without taking the head off first.

Hope that may help.

Scott