Club 80-90 Forums

Hi,
Got an '86 T25 AAZ diesel home-brew Transporter.
Had on-going issues with coolant system since a hose burst a few months back, and a pretty big overheat of engine. I realise it could be a big problem with gasket/head or worse but I am just trying to do the easier/cheaper bits first to rule them out.
Very long story, parts changed (thermostat , dalek cap, heat coolant temp sender), things tinkered with. Been bleeding it at rad forever and air in the system at that point, and water blowing back into tank behind number plate to the point of it blowing under pressure, coolant light flashing straight from start up and now the heater in the cab isn't blowing out hot air either (it blows at 3 speeds but only cold, and the fuse went a few weeks ago)- any ideas on what to try next?
I guess a clean out of the heater matrix would be advised?
I can't find a tutorial on doing it and not even sure how to get at it...? Remove dash and in the sealed unit with motor/blower fan? Behind the radiator? or above where spare wheel is located?
Any help appreciated.
Thanks in advance

To be honest doesn’t sound like the heat matrix is causing the issue. It sounds like an air lock and if you have badly overheated the engine then the head or head gasket are prob toast and it’s combustion gasses blowing your coolant out...
Flushing the heater matrix should be simple enough from the engine bay via the feed and return. But usually if they are blocked, you will need to replace it. (Same with radiator, if it’s blocked you will never get it clean really)

There are plenty of threads regards the “dash out” and “heater fan replacement” as that’s essentially what you are doing if you want to change the heater core

It’s not rocket science. But it is time consuming... make sure you have disconnected the battery before dismantling as you can easily short a wire out...

toomanytoys wrote:To be honest doesn’t sound like the heat matrix is causing the issue. It sounds like an air lock and if you have badly overheated the engine then the head or head gasket are prob toast and it’s combustion gasses blowing your coolant out...
Flushing the heater matrix should be simple enough from the engine bay via the feed and return. But usually if they are blocked, you will need to replace it. (Same with radiator, if it’s blocked you will never get it clean really)

There are plenty of threads regards the “dash out” and “heater fan replacement” as that’s essentially what you are doing if you want to change the heater core

It’s not rocket science. But it is time consuming... make sure you have disconnected the battery before dismantling as you can easily short a wire out...

Thanks for reply - yes, had the dash and everything out before, so changed those awkward bolts already.
I will just give it a clear through from engine bay and from then see what happens and see if hot air returns in cab.

In terms of next steps...I guess it's got to be head and/or gasket
Having read this thread, I think many of the issues are similar to mine and this might be an (even worse?) possibility ?
https://club8090.co.uk/forum/viewtopic.p ... 6&start=15" onclick="window.open(this.href);return false;

Just done one with exactly the same symptoms, overheat caused by blown hose , warped head but no cracks so skimmed head and new head gasket sorted it !

Flakey wrote:Just done one with exactly the same symptoms, overheat caused by blown hose , warped head but no cracks so skimmed head and new head gasket sorted it !

Cheers Flakey - I think I might be going in this direction. I just wanted to try the cheaper options first. But probably just delaying the inevitable.

I know there are members here who point out that VW don't recommend a skim on this head, but then again there are folk who like you went down that route and sorted it.

Thanks