Disco 2 Heater, coolant, head gasket

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Bantam1

Bantam1

Well-Known Member
Posts
1,627
Location
North Wales, UK
OK I went to the Td5 yesterday afternoon (not been in it all week) checked coolant level and as I opened the header tank cap it hissed away (its done that before). Topped up and bled it and took it for a run. All good on the run but on the way back the heater started blowing cold (its done that before too). This morning I opened the header tank cap, the level was well above the level I topped it at the previous day, and it spurted out coolant everywhere. Engine temp is always ok by the way; a tad over half way anyway and the car starts and runs like a dream every time I use it.
Now when I got this disco I found the coolant to be red rust in colour and spent an age flushing it out and then I suffered a hose burst (could this have been pressure from a head gasket issue?), the small hose tucked away behind the turbo.
I've read a few threads on here and it seems I may have a gasket issue, so today I have mostly been taking the head off my Td5.
 
Taking the head off has taken some 6 or so hours, mainly because I've not done a Td5 before and the viscous fan would not come off. A broken fan spanner and the need to make a new one and a pulley holder to get it off took a good deal of this time.
Anyway its off now, I've checked the head and block for straight and all looks ok. As I said above the engine ran great so I have no concerns over it other than the gasket itself.
So what did I find? Well I can see the hone marks in the bores and the valves and pistons all look quite clean and not as sooty and cruddy as I had expected. I am wondering whether someone has done a rebuild or whether at 74k the engines actually look like this, half run in!
I couldn't see a clear point where the HG may have been pressurising the coolant but the drillings look close to the bores so its no surprise these things suffer from such issues. However the HG was disturbed as I took the head off so I probably couldn't have expected to spot anything, it would have to be small anyway and its only been a recent thing.
I did however find that the dowels were the plastic variety and badly distorted. Could this be a bit of head movement that has caused the HG coolant issue?
Having the plastic dowels, does this date the HG to an early date? If someone had been in there in the past 10 years would they really have put plastic dowels in?
The pistons are marked as follows if anyone can tell me whether they are oversize or not; ERR7179 - F51 - 27.
 
I'll be ordering the headset and bolts Monday with a view to replacing the head next saturday.
There are however a few things I'd like to look into like, why does it need a fuel cooler and can I remove it altogether?
 
It’s maybe had that radweld rubbish in at some point.I once had an escort van and that took ages to flush it all out.i had nowt but hassle with that coolant system
 
Bantam1 said:
so I have no concerns over it other than the gasket itself.
Click to expand...
When I said I had no concerns I didn't but after reading everything I can find I now have concerns that I should test the head first.
Do these heads crack and pressurise the coolant system or is that issue solely a gasket issue compounded by the plastic dowels?
I've had no overheating, or at least my temp gauge hasn't said so.
Is cracking limited to an injector fuelling channel witnessed in the combustion area, which I don't have?
 
Pic of the plastic dowels.
One is distorted more than the other but is that all it takes??

IMG_0252.JPG
 
Looking at the state if those dowels, I'd say your head has definitely "moved". As far as I'm aware, that's enough to cause the coolant loss issues you've experienced.
 
CliffordGarrett said:
Looking at the state if those dowels, I'd say your head has definitely "moved". As far as I'm aware, that's enough to cause the coolant loss issues you've experienced.
Click to expand...
Thanks Clifford I would like to think its just that and I just need to replace the dowels with steel and put a new HG on.
She's and old engine from 1998 but only done 74k.
 
Well, it fixed mine. The water gallaries, as you commented, are close to the cylinders, so it only takes that small shift from alignment to allow water to enter cylinder(s) and evaporate. Also will pressurise the coolant system. It's a classic common fault on the early 10P Td5. There is a chance rhat the head may have cracked, but I think those plastic dowels help mitigate against this. There is advice from LR that you shouldn't replace them with steel ones on the 10P heads due to risk of cracking, but I only know of one member here who has followed that advice. Mine are steel now and so far so good - about 4 or 5 years now.
 
The preload provided through the head bolts is quite high and you could be forgiven for expecting that the preload alone might keep the head from moving.
However, a running engine opposes the preload with each combustion and maybe just enough that the head could then move.
Hence why all heads, including every motorbike and car I have ever known use steel dowels to hold the head in alignment.
It would appear the rover K series and these early td5 engines decided to screw convention and go with their own idea.
Mines done 74k. I wonder if there is a mileage period between which these issues start to show.
 
CliffordGarrett said:
Well, it fixed mine. The water gallaries, as you commented, are close to the cylinders, so it only takes that small shift from alignment to allow water to enter cylinder(s) and evaporate. Also will pressurise the coolant system. It's a classic common fault on the early 10P Td5. There is a chance rhat the head may have cracked, but I think those plastic dowels help mitigate against this. There is advice from LR that you shouldn't replace them with steel ones on the 10P heads due to risk of cracking, but I only know of one member here who has followed that advice. Mine are steel now and so far so good - about 4 or 5 years now.
Click to expand...
I wonder why they are concerned that the dowel would crack the 10p head and not the 15p?
The 15p may be a bit thicker in that area and capable of coping with the fatigue stresses or they have just said that to avoid a host of claims that they produced engines that were not fit for purpose in the first place.
4 / 5 years sound good to me though.
 
Makes you wonder. Same with the "cannot skim the head" situation. Due to the miraculous difference the "case hardening" makes, or the sale of replacement heads?
Check your water pump BTW, these leak coolant too. Not so obvious before they fail altogether.
 
So this weekend, 24th Feb, I am putting the head back on with steel dowels.
Been to machine shop, who just want to skim and test everything for loads of money, and to local 4x4 specialist who hedge their bets when giving out advice.
Therefore I've considered and looked at everything myself and I've decided I don't need a pressure test or a skim, just a new head gasket and steel dowels.
I have checked the head for true using a steel rule (1m long) and its perfect, I also did not take the head off because of overheating and therefore I don't expect any issues.
I've therefore cleaned both head and block to remove all signs of the old gaskets and scrutinised the head in all the places you might expect cracking if overheated and all is looking good.
So on it went today and I've re-used the old head bolts because they are not yield bolts (no necking areas) all tightened up and ancillaries on, but I haven't finished it yet because I had to do some other things around the house. Hopefully all finished tomorrow.
My hands are ripped to bits and I ache all over. This has not been as easy as the defender 200tdi I must say.
 
I've taken the opportunity to put a new thermostat in too. What a pain in the arse job that was (like others).
If I get it going again I'll do a fluids and filters service separately.
Back to bathing my hands....
 
And all done!
Started up great, runs as it should, only difference is it isn't pressurising the coolant.
I've run it on a good run twice now and heater is fine, temperature is fine and coolant hoses are not pressurised.
So the moral of this story is as soon as you get a cooling system pressurisation issue get a new head gasket on it quick.
If you do you should change the plastic dowels for new steel ones but you can re-use the heads bolts and the turbo to manifold gasket too.
Oh yes I re-used the rocker cover gasket as well, just cleaned it up and when I put it back on I used some RTV as I use on my motorbikes to give a better seal.
A good few hours work (10 in my case) but for the cost of a head gasket, antifreeze and a bit of RTV, why wouldn't you?
 
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