Fixing snapped cambelt damage!

Fixing snapped cambelt damage!

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dai1983

Original Poster:

2,902 posts

148 months

Thursday 23rd October 2014
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My Mother in laws inlet pully failed on her MK1 Megane causing the belt to come off and the timing to go out etc. we are considering her options which are: fix the engine, source a second hand one or buy an unknown but likely to be cheap car!

I've found complete head repair kits which include 16 valves, head bolts, seals, gaskets, cambelt, water pump etc for £50 - £100 less than a 2nd hand engine. I work as a mechanic (glorified fitter really) in a HGV/land rover workshop so have access to most of the equipment I'd need and there are some experienced blokes here. This type of work isn't day to day as we would just replace the engine on our vehicles so I have a few questions:

-valves will be bent and I know this. Replace all 16 while I'm in there or just the bent ones?
-I've not yet seen the car. The cam pulleys are keyless but is there likely to be damage to the camshaft itself?
-I know a decent machine shop so do I get them to recut the valve seats, don't bother or do it the manual way?
- is it likely other parts of the engine will be damaged? I guess the pistons could be marked?
-any thing else I should be aware of?

Thanks in advance as always,

Dai

thatdude

2,654 posts

126 months

Thursday 23rd October 2014
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Can you get a borescope to look down the spark plug holes to check the pistons? You might also be able to check for any metal bits too. Anything in the sump?

If you can repair it cheaper, go for it. Who knows what history is on a second-hand engine; at elast with a properly, well repaired engine you'll know those parts are not going to fail.

cptsideways

13,535 posts

251 months

Thursday 23rd October 2014
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Far cheaper to buy another complete working car & scrap that one, they are tuppence at that age

shoehorn

686 posts

142 months

Thursday 23rd October 2014
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cptsideways said:
Far cheaper to buy another complete working car & scrap both,they are tuppence at that age
FTFY.


I have done a few of these for failed belts and usually find all but the exhaust valves on one cylinder have hit,which is odd and even so,if you have the head off change the lot,chances are they will be covered in carbon and need re seating anyway,
Plus if you are using a sucker type grinding stick no matter how clean you make that old valve face they just wont stick to them like a new valve facerage
I really fking hate doing modern heads with the piddly,fiddly arsed minute collets in use have now with valve stems/spring caps recessed to what might as well be 2 foot down some fking hole in the head,bd things but I would still do all sixteen.
Also of the few I have done many had completely failed or very shagged water pumps.

dai1983

Original Poster:

2,902 posts

148 months

Thursday 23rd October 2014
quotequote all
That's for the replies. She's considering her options at the mo but she isn't keen on buying a car with issues. Apart from this fault it has been pretty solid. There's also little corrosion of any on it even the underside. The choice would have been easier if it were completely rotten.

Talking of the valves:

-would I need a special valve spring compressor or would a normal one be ok?
-when lapping the vales and seats am I better off sending it to a machine shop or doing it myself? The old guys at work say that it's easy and about 5 mins per valve would be enough.

wildoliver

8,766 posts

215 months

Saturday 25th October 2014
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Is it worth just looking for a good used head?