Line of attack with a failed timing belt...

Line of attack with a failed timing belt...

Author
Discussion

DuraAce

4,240 posts

161 months

Saturday 6th August 2016
quotequote all
Mr2Mike said:
Bent is bent. Valve heads rarely break off from a broken timing belt.
Well yes, obviously bent is bent.

However having stripped a few heads down that have broken belts I have seen several break the heads of the valves and smash them back through the head and the piston crowns.

Never seen this scenario with the engine at idle, yes valves bend but it's a lot easier to fix than when the belt goes at 6k rpm - that looks like a grenade has gone off inside the cylinder.

My point being that rpm does influence the severity of damage done (in my experience)
E-bmw said:
DuraAce said:
therefore will impact the valves many times less than the other.
Once is enough to wreck the lot!
You reckon?

8/16 valves is a lot easier and cheaper to replace than valves, guides, head, pistons etc.
Faster rpm at breakage = more damage done (generally speaking, exclusions may apply) was my original point. You've more chance of resurrecting an engine that breaks it's belt at low rpm vs high rpm.



Edited by DuraAce on Saturday 6th August 13:44

E-bmw

9,240 posts

153 months

Saturday 6th August 2016
quotequote all
DuraAce said:
Mr2Mike said:
Bent is bent. Valve heads rarely break off from a broken timing belt.
Well yes, obviously bent is bent.

My point being that rpm does influence the severity of damage done (in my experience)
E-bmw said:
DuraAce said:
Once is enough to wreck the lot!
You reckon?

8/16 valves is a lot easier and cheaper to replace than valves, guides, head, pistons etc.
Faster rpm at breakage = more damage done (generally speaking, exclusions may apply) was my original point. You've more chance of resurrecting an engine that breaks it's belt at low rpm vs high rpm.



Edited by DuraAce on Saturday 6th August 13:44
And my point being that once is enough to wreck the lot, like I said.

Not once does the same as many times.

Not once WILL cost as much to repair.

Not even once won't break the valves.

"once is enough to wreck the lot"

bungz

Original Poster:

1,960 posts

121 months

Tuesday 9th August 2016
quotequote all
I believe the car was going around 30mph when it went.

Have timed it up and done a compression test, noute, 30psi, noute and noute. Yup valves all bent.

Will take the head off with the view to getting a scrap motor to port the head across too.

bungz

Original Poster:

1,960 posts

121 months

Monday 15th August 2016
quotequote all
Heads off, came apart quite easily in the end.

Most of the valves have had a good kiss from the pistons so will prob look for a replacement.

Anyone got a idea of a price? Would it be cheaper just to get a whole engine?

E-bmw

9,240 posts

153 months

Monday 15th August 2016
quotequote all
Google is your friend under such circumstances.

drdino

1,151 posts

143 months