Taking cylinder head off for inspection - any tips?

Technical questions and answers about the Mazda Bongo

Moderators: Doone, westonwarrior

Locked
User avatar
Simon Jones
Supreme Being
Posts: 9341
Joined: Mon Aug 29, 2005 3:34 pm
Location: Salisbury (ish), Wiltshire

Taking cylinder head off for inspection - any tips?

Post by Simon Jones » Wed Apr 02, 2008 1:29 pm

I'm having problems with excess pressure in the coolant system at the moment. Despite bleeding as per the various methods, the problem still occurs, so I plan is to take the head off for a closer look. I will be using the info in the manual & relevant factsheets in the members section. Here's my list of items to get/change whilst doing this. Is there anything else you recommend & any pitfalls to be wary of?

* Headgasket set inc: Head Gasket, Rocker Cover Gasket, Cam Shaft Seals, Rocker Cover Seals, Valve Stem Seals & Manifold gaskets (inlet and exhaust). I won't bother changing valve stem seals
* Cambelt
* Cambelt tensioner spring
* Cambelt tensioner - is this necessary? It has supposedly been replaced before - do they wear out?
* Head bolts
* Thermostat
* Replace hoses with Flippa's silicon pipes

That little lot comes to a tad under £300 from the club shop, Flippa & Bongobits. Items that I might change:

* Water pump - if the impeller, bearings & seals are ok - is it worth it? What's the typical lifespan?
* Radiator - there are no leaks or obvious hotspots. The water goes in red hot & comes out practically cold. I'll give it another good flush, but I don't believe it will be contributing to current problems. Does anyone know the exact fluid capacity of the rad? I was going to measure how much liquid it holds which would tell me if the capacity was reduced by silt & gunge.

Any advice & comments welcomed. Thanks
User avatar
mikeonb4c
Supreme Being
Posts: 22877
Joined: Sun Nov 05, 2006 10:49 pm
Location: Living with Mango Bongo in the North West but with a tendency to roam
Contact:

Re: Taking cylinder head off for inspection - any tips?

Post by mikeonb4c » Wed Apr 02, 2008 1:34 pm

Simon - have you tried the testing kit that should detect the presence of exhaust gas in the coolant mix as I understand this ought to confirm if it is a leaking head gasket. In which case you probably need look no further for clues as to what needs fixing? :roll:
User avatar
Simon Jones
Supreme Being
Posts: 9341
Joined: Mon Aug 29, 2005 3:34 pm
Location: Salisbury (ish), Wiltshire

Re: Taking cylinder head off for inspection - any tips?

Post by Simon Jones » Wed Apr 02, 2008 1:39 pm

No - any idea where to get/borrow from?
Veg_Ian

Re: Taking cylinder head off for inspection - any tips?

Post by Veg_Ian » Wed Apr 02, 2008 1:45 pm

Well I would say don't bother if you are intent on removing the cylinder head. A bit drastic but at least you will know for definite if a problem with the head. Check the gasket carefully for evidence of cross-contamination between coolant and gas and for cracks in the head. While the head is off clean out all the coolant pathways. Not the most technical method but laying the side of a steel rule across the head at various positions will give an idea if out of true.
User avatar
haydn callow
Supreme Being
Posts: 5777
Joined: Mon Jan 08, 2007 9:50 pm
Location: Somerset
Contact:

Re: Taking cylinder head off for inspection - any tips?

Post by haydn callow » Wed Apr 02, 2008 4:51 pm

You may not see any faults in the head. If you do fine but if not I would take it to be tested by them what knows these things.
http://www.coolantalarm.co.uk
Developer of the Mazda Bongo Coolant loss Alarm
Also BMW Clocks
Aethelric
Bongolier
Posts: 418
Joined: Mon Feb 25, 2008 3:50 pm
Location: Fife
Contact:

Re: Taking cylinder head off for inspection - any tips?

Post by Aethelric » Wed Apr 02, 2008 5:36 pm

Visual inspection sometimes does not reveal much. A few years ago I had to remove the head from a volvo as there was blowby between two cylinders. This was confirmed by the fact that on tick over or low throttle opens it was running on two cylinders, the defective ones were adjacent to each other.
I bought a new gasket, removed the head....and the old gasket looked fine! No marks, nothing on the cylinder head or anywhere. With a heavy heart I put the engine back together with the new gasket and after a "no fault found" I was sure there would be no improvement. It was fine!! and was still fine around 20,000 miles later when it was sold on.
My point is that tests had confirmed the problem, although a close visual inspection, even when I knew what I was looking for missed it.
Dave
Locked

Return to “Techie Stuff”