Causes of cracked cylinder head

jonb · Post by **jonb** » Thu Sep 03, 2009 5:58 pm

Hi all,

After 5 years of ownership, it appears that our Bongo has a cracked cylinder head. Symptoms include carbon deposits in the coolant, gradual loss of coolant, lumpy starting and far too much water vapour in the exhaust gases on start up.

I'm pretty certain that during the last five years (120,000 km travelled) our Bongo has never overheated. What else can cause a cylinder head to crack?

Got a quote for replacement from Ian Taylor in Market Drayton.

Cheers,

Jon

francophile1947 · Post by **francophile1947** » Thu Sep 03, 2009 6:04 pm

If it's never overheated, it could well just be the head gasket

mikeonb4c · Post by **mikeonb4c** » Thu Sep 03, 2009 6:12 pm

I'm sure someone has pointed out before that the heads on diesel engines like ours have to endure a lot of pressure and stress. I guess that there are variations in manufacturing quality and thus some crack before others (just like people then!). But seriously, is it certain that it did not endure any traumas in its working life that may have helped trigger it in to failure?

Interesting one as I can't recall many cases of several years good service followed by a head failure (BF member Dobby may be one though, from poor memory - his has just been fixed and it might be worth PMing him if he doesn't read this)

Good luck getting it sorted. Recommend using good quality components (no cheap ebay heads, and use a proper Mazda head gasket) and an experienced Bongo mechanic.

missfixit70 · Post by **missfixit70** » Thu Sep 03, 2009 6:12 pm

Or this may provide an explanation, mixing of incompatible coolants - http://www.igmaynard.co.uk/bongo/forum/ ... t=+coolant

dobby · Post by **dobby** » Thu Sep 03, 2009 11:01 pm

mikeonb4c wrote: Interesting one as I can't recall many cases of several years good service followed by a head failure (BF member Dobby may be one though, from poor memory - his has just been fixed and it might be worth PMing him if he doesn't read this)

That's me! Our head went recently and Ian replaced it, we had two overheats at roughly a three year interval plus some coolant loss. One theory was metal fatigue? Also, ours went at 80,000 miles and quite a few seem to do that. Could be it's the coolant issue that Haydn's linked post refers to. I'm convinced mine ran hotter for far too long and I didn't realise it. I think that can cause them to go over time with a 'last straw' incident.

If doing the head, then rad, hoses, stat and pump should all be options.

Causes of cracked cylinder head

Causes of cracked cylinder head

Re: Causes of cracked cylinder head

Re: Causes of cracked cylinder head

Re: Causes of cracked cylinder head

Re: Causes of cracked cylinder head