Cam Belt Failure

molening · Jul 4th, 2006, 00:24

Just managed to do Edinburgh - Manchester & back on 1/2 a tank, unfortunatly the fuel economy was due to the return leg being on the back of a truck.

Cam belt failed at 70mph (outside lane) the old girl made it to the kerb but isn't too happy now.

Engine is 1986 cc (B200 I think perhaps someone can confirm) any predictions on damage I believe some of these engines were non interference but not sure about this one.

Any tips apreciated.

Barry

Glen Morangie · Jul 4th, 2006, 01:48

I think you'll find it's an interference engine if it's a UK B200 or B230 - I may be wrong. Sometimes people get away with just bending one valve, but if you were doing 70 mph on the motorway, it's likely the damage will be extensive.

Sadly there's no upside to that, is there!

What you have experienced is the nightmare we all dread.

Mike_Brace · Jul 4th, 2006, 07:42

These are an interference engine but only just. You will have probably bent one or two valves. Very easy to replace. Worth taking head of to see. Should noy be terminal - I've probably a couple of s/h valves about.

Mike

Erling · Jul 4th, 2006, 08:02

I was under the impression that only the B230K motors were interference design. (Got two of those - just my luck!) Admittedly, there may be UK specific models I'm not familiar with.

Would a compression or leak-down test be a good way of testing for possible damages?

Clifford Pope · Jul 4th, 2006, 08:54

That's my understanding too. Certainly my B200, 1993, isn't interference. To settle an argument I tried turning it slowly once by hand when I had the timing belt off for replacement. There was no interference in any camshaft position.
If the valves never project below the gasket line, and the pistons are flat, then it is impossible for them to interfere. Of course a broken valve could do all sorts of damage, not the least being to snap the belt.

Glen Morangie · Jul 4th, 2006, 15:05

That's interesting, I could never understand why later UK B2xx versions should differ from the US equivalents (other than the B230K which has a different head and pistons).

However another 240 owner with a B200 engine snapped a timing belt and related a tale of bent valves - so I assumed they must have a higher compression ratio and 'an interference fit'.

It might have been he was 'done' by his local garage - but it sounded reasonable at the time because many manufacturers had increased compression ratios to get better mpg.

So are they definitely non - interference other than the B230K?

Clifford Pope · Jul 4th, 2006, 15:59

This is one of those elusive topics - everytime you think you know where you are, someone else comes along and confuses the issue!
I used to hear it said with authority that ALL the 240 engines were non-interference except those with "heron" heads. I never discovered what they were (B230?) before someone else came along and said "heron" was a misnomer and they weren't true herons, but anyway that wasn't what made an engine interference.
So now I am only certain of one engine - mine- that I actually tested.

As I suggested, there may be other things that can fail in the valve train that do damage and end with a broken belt, it doesn't follow that the belt caused it. Suppose a spring breaks and lets the valve protrude further, or a valve snaps? Or as has just happened to someone on Brickboard, the camshaft appears to have seized through poor lubrication and snapped the belt.

Glen Morangie · Jul 4th, 2006, 16:25

The B230K has the Heron head - it's flat with combustion chambers shaped in the pistons - from a Heron Racing design apparently (I think Erling said that in another thread).

I have heard conflicting info on B2xx interference engine design, but assumed the confusion might have arisen because earlier (B2x) designs were non- int.

Other possible causes of confusion might be -

The design may have changed again in '92 with the extended service interval and round tooth timing belt.

If the B2xx engines for the UK were skimmed to the 'max' to up the mpg without redesigning the head - so the valves were 'at the point' of interfering with the pistons, then if the head or block were ever skimmed (common on overheated heads), it would become an interference engine.

Maybe if two gaskets are fitted an interference engine might become non-int!

Mike_Brace · Jul 5th, 2006, 07:53

I remember fitting a couple of valves to a B200 - probably an older one. That engine definitely was an interference fit. The only time I've had that with any of the engines when a belt has gone - not a common occurrence fortunately. I always carry a spare belt myself just in case.

Mike

molening · Jul 5th, 2006, 21:02

Thanks for replies all.

I am back down south again after having to hire a car.

I will get back to have a look at the engine next week so I will post how it goes.

I am tempted to put a belt on it and see what happens comments on this aproach welcome.

Thanks again Barry

Jul 4th, 2006, 00:24	#1
molening New Member Last Online: Dec 28th, 2009 23:45 Join Date: Jan 2006 Location: Edinburgh	Cam Belt Failure Just managed to do Edinburgh - Manchester & back on 1/2 a tank, unfortunatly the fuel economy was due to the return leg being on the back of a truck. Cam belt failed at 70mph (outside lane) the old girl made it to the kerb but isn't too happy now. Engine is 1986 cc (B200 I think perhaps someone can confirm) any predictions on damage I believe some of these engines were non interference but not sure about this one. Any tips apreciated. Barry

Jul 4th, 2006, 01:48	#2
Glen Morangie Economy motorist Last Online: Aug 13th, 2022 07:48 Join Date: Dec 2004 Location: London	I think you'll find it's an interference engine if it's a UK B200 or B230 - I may be wrong. Sometimes people get away with just bending one valve, but if you were doing 70 mph on the motorway, it's likely the damage will be extensive. Sadly there's no upside to that, is there! What you have experienced is the nightmare we all dread. Last edited by Glen Morangie; Jul 4th, 2006 at 01:50.

Jul 4th, 2006, 07:42	#3
Mike_Brace Former contributor Last Online: Jul 2nd, 2022 07:54 Join Date: Dec 2004 Location: Rhosgoch, Anglesey	These are an interference engine but only just. You will have probably bent one or two valves. Very easy to replace. Worth taking head of to see. Should noy be terminal - I've probably a couple of s/h valves about. Mike __________________ A Volvo is for life not just for Christmas!

Jul 4th, 2006, 08:02	#4
Erling VOC member Last Online: May 8th, 2007 20:15 Join Date: Dec 2001 Location: Stavanger	I was under the impression that only the B230K motors were interference design. (Got two of those - just my luck!) Admittedly, there may be UK specific models I'm not familiar with. Would a compression or leak-down test be a good way of testing for possible damages? __________________ The older I get, the better I used to be.

Jul 5th, 2006, 07:53	#9
Mike_Brace Former contributor Last Online: Jul 2nd, 2022 07:54 Join Date: Dec 2004 Location: Rhosgoch, Anglesey	I remember fitting a couple of valves to a B200 - probably an older one. That engine definitely was an interference fit. The only time I've had that with any of the engines when a belt has gone - not a common occurrence fortunately. I always carry a spare belt myself just in case. Mike __________________ A Volvo is for life not just for Christmas!

Jul 4th, 2006, 08:54	#5
Clifford Pope Not an expert but ... Last Online: Yesterday 12:45 Join Date: Dec 2001 Location: Boncath	That's my understanding too. Certainly my B200, 1993, isn't interference. To settle an argument I tried turning it slowly once by hand when I had the timing belt off for replacement. There was no interference in any camshaft position. If the valves never project below the gasket line, and the pistons are flat, then it is impossible for them to interfere. Of course a broken valve could do all sorts of damage, not the least being to snap the belt.

Jul 4th, 2006, 15:05	#6
Glen Morangie Economy motorist Last Online: Aug 13th, 2022 07:48 Join Date: Dec 2004 Location: London	That's interesting, I could never understand why later UK B2xx versions should differ from the US equivalents (other than the B230K which has a different head and pistons). However another 240 owner with a B200 engine snapped a timing belt and related a tale of bent valves - so I assumed they must have a higher compression ratio and 'an interference fit'. It might have been he was 'done' by his local garage - but it sounded reasonable at the time because many manufacturers had increased compression ratios to get better mpg. So are they definitely non - interference other than the B230K?

Jul 4th, 2006, 15:59	#7
Clifford Pope Not an expert but ... Last Online: Yesterday 12:45 Join Date: Dec 2001 Location: Boncath	This is one of those elusive topics - everytime you think you know where you are, someone else comes along and confuses the issue! I used to hear it said with authority that ALL the 240 engines were non-interference except those with "heron" heads. I never discovered what they were (B230?) before someone else came along and said "heron" was a misnomer and they weren't true herons, but anyway that wasn't what made an engine interference. So now I am only certain of one engine - mine- that I actually tested. As I suggested, there may be other things that can fail in the valve train that do damage and end with a broken belt, it doesn't follow that the belt caused it. Suppose a spring breaks and lets the valve protrude further, or a valve snaps? Or as has just happened to someone on Brickboard, the camshaft appears to have seized through poor lubrication and snapped the belt.

Jul 4th, 2006, 16:25	#8
Glen Morangie Economy motorist Last Online: Aug 13th, 2022 07:48 Join Date: Dec 2004 Location: London	The B230K has the Heron head - it's flat with combustion chambers shaped in the pistons - from a Heron Racing design apparently (I think Erling said that in another thread). I have heard conflicting info on B2xx interference engine design, but assumed the confusion might have arisen because earlier (B2x) designs were non- int. Other possible causes of confusion might be - The design may have changed again in '92 with the extended service interval and round tooth timing belt. If the B2xx engines for the UK were skimmed to the 'max' to up the mpg without redesigning the head - so the valves were 'at the point' of interfering with the pistons, then if the head or block were ever skimmed (common on overheated heads), it would become an interference engine. Maybe if two gaskets are fitted an interference engine might become non-int!

Jul 5th, 2006, 21:02	#10
molening New Member Last Online: Dec 28th, 2009 23:45 Join Date: Jan 2006 Location: Edinburgh	Thanks for replies Thanks for replies all. I am back down south again after having to hire a car. I will get back to have a look at the engine next week so I will post how it goes. I am tempted to put a belt on it and see what happens comments on this aproach welcome. Thanks again Barry

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