21 Turbo Cooling system pressurisation.

[Renoholic]

Hi,
21T owner from New Zealand. It's been a while since I posted but now I'm in dire straights. I've been poping and bursting radiator hoses lately and replaced many of them since. I made a gadget that connects to a bleeding nipple with a pressure gauge sitting outside makeshift on the wiper blade. The weird thing that I noticed is that this water pressure gauge acts the same as the boost gauge. The pressure stays low or when cold on zero. As soon as I accelerate a little and the boost starts to climb, even a little like a 25% of the gauge, the water pressure gauge does the same, and when I change up to or slow down the boost gauge drops and so does the water gauge. The 2 gauges are synchronized!
Can anybody think what the reason could be? Is there somewhere on the pressurized intake side a possibility that a crack could go into the water system? Could there be heating channels in the intake manifold that has a crack where the boost can go in? Or in the head?
Is this perhaps a blown head gasket? I don't think so because when the car is hot and the cooling system is pressurized by the heat then the pressure remains for hours until the engine has cooled down.
I will love to get this fixed because I love the car and it is used to tow the race car, R8 Gordini, a perfect combination.
Regards, Renoholic.

 

[Duncan Grier]

Prob one for @DaveL485 as a fellow R21 lover

But would be worth checking there is no restriction/block in coolant system including rad itself

In my experience, water pump/block/restriction has led to coolant header tank spitting its dummy

Head gasket failure or a crack in system could also be cause any tell tale other signs of HG failure? Poss do a sniff test?

 

[Big Steve - Raider]

First thought is head gasket like @Duncan Grier mentions… but let’s see what the 21 Turbo font of all knowledge says @DaveL485

 

[DaveL485]

Thats very head-gasket sounding. Compression test it, see if you are down on one of the cylinders.

The cooling system is supposed to blow off pressure at 23.6psi via a spring valve in the expansion tank cap, this is to prevent popping hoses and rad cores if it pressurises. Does it have the original white cap with blue centre? What pressure are you seeing on this gauge you rigged?
If you run the engine at fast idle with the expansion tank cap off from cold, does it push coolant out the top of the tank? Are you losing coolant when driving normally? Is there any sort of misfire on cold start that then clears after a few seconds?

EDIT: the only place turbo boost pressure could leak into the cooling system is the cylinder head inlet ports, but i've never seen any engine do that let alone a 21 Turbo engine.

 

[Steve Swan]

Had an odd head gasket issue years ago in which the car ran fine, but the cooling system pressurised way beyond what it should. It would take ages to do this and you could let off the pressure and continue on your way no problem. It was a hairline mark on a firing ring that was the cause. No mixing, no overheating, nothing to point you in the HG direction, except pressure. Yours sounds more interesting in that it is boost related, like a seal on the inlet manifold to water jacket which allows boost into the water system, but not quite as much pressure as a cylinder pressure issue would. Can you test the coolant for combustion gases?? like litmus paper they change colour , that would be the acid test perhaps (if you will pardon the pun) Looks like it will have to come apart. It will make a change from a Gordini motor though.

 

[DaveL485]

like a seal on the inlet manifold to water jacket which allows boost into the water system

Nothing on the 21 like that unfortunately, it'd have to be a crack in the actual alloy of the head.

 

[Steve Swan]

I had assumed there was some sort of water jacket on the inlet manifold for heating/cooling, but you know what they say about assumption.....

 

[Brigsy]

Exhaust gasses in the coolant at a guess due to headgasket on its way out, had same issue on a gtt years ago.

 

[Renoholic]

Thanks for all the comments and tips. Unfortunately it looks like no quick fix. I thought the same as Steve that there could be a water heating channel in the inlet manifold like the Renault 16TS, but if Dave says no then I accept it is no. I will do a quick compression test or maybe a leakdown test.

The next step and question will be..........where do I get a head gasket? is that a straight forward operation and are the bolts normal ones or stretch bolts?

Any other warnings for me 21T related? Special Goo on the gasket or just a dry install? I will do the cambelt as well. I have found some spares on Websites with reasonable prices but then ridiculous shipping costs. Any shortcuts on that?

Thanks in advance and I will start reading the Haynes manual.

Renoholic.

 

[DaveL485]

where do I get a head gasket?

I can supply you a head gasket set. You'll need the set, not just a HG.

is that a straight forward operation and are the bolts normal ones or stretch bolts?

It's not too bad just follow the process (I can summarise if you need), plan on changing belts and fluids while you are there. I'm literally half way through one now. Bolts are 10.9's you can re-use them.

Any other warnings for me 21T related? Special Goo on the gasket or just a dry install?

Dry install, no goop on ANY of the gaskets. Warnings, yes, three stage tightening of bolts in the right order, then you MUST retorque them after running it up to fan temp, again the the correct order.

I will do the cambelt as well.

Make sure it's 115 teeth by 19mm (3/4"). I can probably send you any parts you can't get over there.

 

[Renoholic]

Thanks Dave!! I will definitely contact you again a little later as I have just started building my new shed and plan to be done in a month.

 

[Renoholic]

Hi,
The time has arrived. I mentioned above that the shed will be built and completed soon, that was February, slightly behind schedule isn't it.

Oh well it is done and waiting for the first job to initiate the new workshop. So @DaveL485 , could you please enlighten me in the process of getting a head set from you and maybe a belt as well?

Thanks, Renoholic.

 

[DaveL485]

Well, I will price the stuff, add postage, you send me the cash (paypal, transfer, whatever), I send you the parts assuming everything is available! Do a list of what you need.

 

[Renoholic]

Thanks Dave,

All I can think of is the gasket set, timing belt, and a water pump. I can do tensioners from here.

If you can think of anything else tell me.

Thank, Renoholic.

 

[DaveL485]

OK, bit busy today, DM me later in the week and ill see what I can drum up