M16a headgasket

Hi guys, 
despite hoping it wasn't, I'm airing towards thinking my head gasket has gone. It's yet to over heat on the guage so now is the time to act!
My symptoms are;

Water sloshing noise from inside the cabin when revved,
Smelling very (very) hot after every drive especially higher speed motorway journeys, 
Coolant expanding into the expansion tank when hot but not being sucked back in when the engine cools even when left overnight!

What I've done so far;
M16a Liana conversion back at Christmas with a brand new radiator fitted at that time.
New genuine rad cap and thermostat last week.
Waterpump removed, inspected and refitted (perfect condition).
Coolant system cleaned and flushed through using a Holts additive.

I have diagnosed my viscous coupling is not working, while I will get a new one, as a temporary measure I purposely seized it up so the fan is working permanently. I wouldn't recommend this normally as it feels like it's sucked 10bhp from the engine and makes loads of noise but for a diagnosis purpose, it's not changed my symptoms at all.

I have also read about the pipe in the expansion bottle getting longer over time and touching the bottom of the bottle, blocking the coolant returning into the rad. While mine had definitely got longer, I cut an inch off to be safe but this also has not changed my symptoms at all. 

So we are where we are... I'm almost convinced now that it is the head gasket.

I guess my main question is having done the m16a conversion, I'm assuming the gasket is different to the m13a? I no longer have the reg of the donor car for parts... or is it as easy as asking for a gasket for an engine rather than a car? 
A secondary question is regarding the work... I'm pretty confident but never done a head gasket on a chain engine,  do you have to change the tensioner? Assuming it's hydraulic? What about the chain sliders?

Any thoughts or tips would be greatfully received!

Many thanks
Ben

I can't see why it would be a different gasket. The increase in capacity is from a longer stroke rather than a bigger bore. The cylinder heads are all identical. But if in doubt, scour the calssifieds for a similar age liana for sale and use that reg to order.

I'm not seeing/hearing any evidence of a leaking head gasket ...

- do you have signs of oil/coolant cross contamination?
- have you tested the coolant for the presence of hydrocarbons?
- have you done a compression test and leak down tests?

Coolant sloshing sounds in the cabin when revved is a sign of low coolant in the heater circuit.

Coolant not returning from the expansion tank will cause low coolant, which can cause the sloshing sounds, any cooling system leak can cause coolant not to return from the expansion bottle and the most common cause of coolant not returning is a defective radiator cap.

Eliminate the simple things, do the necessary tests before you pull the head.

If as reported you have either inspected or replaced all the ancillary cooling system parts then yes it's time for a head gasket for. Busta is onto a winner with the suggestion of a borrowed reg for parts orders.

As Fordem says, rad cap! They are a common failure with the same symptoms.

Guys read the original post. It has brand new rad cap I know it's a common issue.
New genuine rad cap
New genuine thermostat
Water pump is in perfect condition
The radiator was new at Christmas.
Engine was out of a 70k mile car.

The rad level is low everytime when checked and its always exactly the amount that is in the expansion bottle but hasn't returned...

I've not done a leak down test nor do I have the equipment.
I'm not particularly worried about doing the head gasket, I've done lots in the past (old fords), I was more after tips on the job itself and acquiring the parts.

Thanks for your reply

Ben

I had a garage do my last one as it needed a clutch too so I haven't had one apart to offer direct experience. From the account of the garage it was a fairly simple job.

'The rad level is low everytime when checked and its always exactly the amount that is in the expansion bottle but hasn't returned...'

In comparison to the radiator the expansion tank doesn't hold much water so if the loss from the radiator is the same as the excess in the expansion tank it suggests you aren't loosing any water, it is just getting re-positioned. I wouldn't have thought that re-positioning of the water from rad to expansion bottle would cause an over-heat.

However, you also mentioned water sloshing in the heater matrix, which does suggest you are loosing water somewhere.

It could be a head gasket, pressurising the water system, do you see any bubbles in the coolant expansion tank when running (hot)?

What do the plugs look like, any hint of a head gasket failure?
Or, the oil, any hint there?

You seem to have checked all of the pipes etc, but what about a heater matrix fault, you might not notice a leak in there?

Usually when the heater matrix dies it mists up the windshield big time and won't clear. That's what my last jimny did and my old polo did it too.

The remaining quantity of coolant in the rad and the expansion bottle indicates there is no leak anywhere else.
I've have just had a good rummage under the dash and there is no sign of a leak there...

The coolant normally heats up, pressurises the system, opens the rad cap and expands into the expansion bottle.
My theory is if the head gasket failing is pressurising the system, it opens the rad cap and pushes out coolant. When you turn the engine off it immediately closes the rad cap as the pressure goes, therefor not allowing the water to return into the rad as it cools..
Might be wrong but, having replaced most of the cooling system I can't think what else it could be... as I said I'm happy to do it, just need to order the right bits!

This is exactly what mine was doing.

wrote:

The rad level is low everytime when checked and its always exactly the amount that is in the expansion bottle but hasn't returned...
 

See that line there?  If that is the only symptom on which your diagnoses is based, then you're quite likely to have the same symptoms on reassembly.  The chances of that being a leaking head gasket is slim to non existent.  If you have enough combustion pressure leaking into the cooling system to force coolant out of the pressure relief valve, it will be enough to fill and overflow the reservoir

For some reason your cooling system is unable to develop a vacuum as it it cools - most likely a leak between the neck of the radiator and the overflow reservoir (and yes, that includes a cap that doesn't seal properly)  I've had this issue and traced it to a crack in the overflow reservoir cap - when the coolant in the system expanded it would flow over to the reservoir but when it cooled, instead of the vacuum lifting the coolant out of the reservoir, it would suck air in through the crack.

The radiator cap is not as simple as you might think - it has three separate points at which it can leak - the pressure relief valve that opens to allow flow outwards is the first, the return valve that allows flow inwards is the second, and the third is where the cap seals to the neck of the radiator.