RRC 3.5 V8 - Still headgasket issue ?

[jako]

Hi All!

 

I bought a 1984 RRC 4-Door classic with the 3.5l engine with twin SU carbs in Nov. I got it super cheap as the engine needed new headgaskets. I took everything apart, replaced the cam, lifters, timing chain. I resealed the water pump and oil pump and new gaskets everywhere. I (stupidly?) bought tin headgaskets instead of composite but as I got a pair of heads from ebay within spec (got these checked) for less than what a skim&check would cost here in Sweden I thought it would be ok. The car has been running well for a few weeks, always starts but I've been having trouble with the cooling system not always building pressure and the temp gauge 'dropping' to zero unless I open up the expansion tank cap to sort of release the pressure (I assumed it was airlock.)

It's gradually been smoking more and more (especially during idle and when cold). However yesterday it was basically a locomotive and noticed the coolant had stopped being clear and was now a much dirtier looking colour. It was basically a jacuzzi in the expansion tank. 

I feel like it's an open and shut case of headgaskets, but I just wanted to double check with you experts! I could definitely do a composite head gasket swap in a matter of hours at this stage, but just want to double check before I take the plunge on new gaskets, + oil and coolant. 

It could be a cracked block but that wouldn't explain why it's only starting to smoke lately ? Mind you I haven't drive more than 500km. Any tips would be greatly appreciated. 

 

Here is a link to show the problem: 

 

[elbekko]

I would agree that that does look like the head gasket has gone Especially if it isn't building pressure in the system while bubbling like that, it has to be going somewhere, and by the looks of that exhaust, it's into the combustion chamber.

A cracked block is certainly a possibility, especially if you don't know what the previous owner did to the poor thing. If the headgaskets were blown, and he did keep driving it while overheating, all bets are off.
But start with taking off the heads and looking for obvious leaks there.

Did you follow the 14-bolt or the 10-bolt tightening sequence for the heads?

[smallfry]

The temperature gauge dropping to zero suggests the sender in the manifold is NOT immersed in coolant, so does indeed suggest an airlock.

On the peak of the inlet manifold is a small hose which leads to the top of the radiator IIRC, and the small hose connection to the inlet manifold is prone to blocking with corrosion, and this will cause an airlock causing the symptoms you describe.

Disconnect the radiator end with the engine running, and you should get a flow through it at all times, hot or cold. If not, manifold end is blocked and will need clearing.

Hopefully this will cure your problem, but I fear damage may already be done.

The 3.5 does not usually suffer from block cracks, unless it has been frozen, but as you are in Sweden this could be likely.

There are other things but try this first.

[FridgeFreezer]

13 hours ago, smallfry said:

The temperature gauge dropping to zero suggests the sender in the manifold is NOT immersed in coolant, so does indeed suggest an airlock.

Cheap thermostats don't always have the bleed hole at the top, that can cause issues.