Opinions - scrap cylinder head?

[silvertail]

Hi all,

Dismantled some of my engine's valve assemblies last night, and it looks like the valve guides have had a rough time - all four I checked have been broken!

http://img52.imageshack.us/img52/448/brokenvalveguide.jpg

In my opinion this is damage that can't be repaired (unless someone knows how to remove & replace the guide inserts) and so I should scrap the cylinder head. The other question is - how badly was the engine treated to allow this to happen to at least four valves?

However I'm an engine novice, so I thought I'd ask you loverly fellas :D what you think. Is it usable/fixable, or shall I use it to make a special ornamental table like they have on Top Gear? :rolleyes:

Cheers, Mike

[twinturbo]

Yeah, if it's something like a 1.8 CVH head then bin it. If it's a 1930's Lagonda head then fix it.

TT

[Bonzo]

The photo is a little fuzzy & gives very little clue as to what engine the head is off ;)

It has been my experience that this type of damage is typical of a cam belt failure at some point in it's life :rolleyes:

Sometimes when a cam belt fails, you'll be lucky & only bend a few valves .... Other times it will destroy some casting around the guides and FUBAR some of the piston crowns !!?? :eek:

At the end of the day, unless it is somthing realy exotic or rare, it'll be way more ecconomical to replace the head .

[twinturbo]

From his other posts, I think He has a Twincam. They are not known for chain failures, but if it did then it would do a lot of damage..

TT

[RAYLEE29]

hi, its no major problem to fit new valve guides just press out the old ones press in new ones and lightly recut valve seats if you cant diy then ask your local engine reconditioners for a price.
What engine is it?
Ray:)

[silvertail]

Hiya, thanks for the posts - and sorry I should have mentioned what engine it was! :o It's an I4 DOHC jobby out of my donor Sierra.

And yes, I know it's a crap engine, but it was cheap to get!

You've all made a lot of interesting points relating to timing chain failure. The chain tensioner often gets mentioned as a weak point in this engine, if this did slip the chain then maybe what I'm looking at is a cheap bodge job to get the engine working again. The valve guide damage isn't the only bad bit about the cylinder head - there's several other faults such as bearing surface scoring, bruising to the head surface..... :(.

I think the best option is to scrap at least the cylinder head. Last time I was down at the local scrapyard (G&W Bridges on the M23) there were plenty of I4s available to scavenge - should be able to pick up a better one for little cost. Or maybe source a Zetec instead :D

RAYLEE, thanks for your comment about pressing in new valve guides - I would have taken that option if there weren't other problems with the head.

In the meantime I'll finish cleaning the cylinder head and get to work on an ornamental glass table. :D

[AshG]

its not hard to fit new guides but you would be better off weighing in the engine and using the cash to buy a zetec.

[Enoch]

What can often happen with these engines is that there are a couple of bolts in the timing chain area that can work loose and get themselves between the chain and lower sprocket. The damage done is the same as when a cam belt breaks. I wouldn't mind betting that's what happened to your engine. Those guides look like bent valves have crashed in to them. I would be very wary about the entire engine and would strip it right down for a really good look, all those bits of metal went somewhere.

[RAYLEE29]

Its a shame you dont live near me ive got a whole engine sat there its no use to me water pump was gone but it still ran
I decided it was too heavy especially after seeing the flywheel also weighed the mt75 and the type 9 was lighter
Ray:)

[silvertail]

Yep, I've checked the rest of the engine block and it's not actually in too bad a state... The only big problem is the rear oil seal was leaking oil into the gearbox bell housing. :mad:

I'm seriously considering getting a Zetec now!