Thread: 186 Cooling System

186 engines are like any other, as they warm up the cooling water expands. If not fitted with an expansion tank the radiator top tank should never be filled more than half full at cold otherwise it will spit out coolant.

You may of course have a blown head gasket, which is a quite easy job to fix on a 186. A temporary cure is to remove the centre of the thermostat or drill a few holes in the perimeter of it. As it will run colder that way it may run poorer (need choke for longer).

From memory the LR radiator has a pressure cap set at around 5psi, so there should be some pressure in the cooling system.

5psi should give a bit of a "sssss" as I release the cap. I get zilch. From my experience, MG's etc are about 7psi and are well known for overheating in Oz conditions. When I released caps on hot engines I got an almighty cough & water spewed out as the pressure was released. Had they been atmospheric, they would have run dry in 10mins.

I might try a new cap.

Head gasket is new & I don't have the usual blown gasket symptoms of bubbles seen thru the rad filler neck.

Did the 186 HAVE an expansion tank?

Originally Posted by geodon

Did the 186 HAVE an expansion tank?

No it had a mark on the radiator top tank to fill to. Many people fitted one though as the cap was set to one side, and if you parked front to the kerb on a hot day you would lose some coolant. Holden's had a kit available.

From memory holden 186 radiator caps were 13 psi.
I run an overflow tank on my 186, but i have a holden radiator.
No doubt you should be able to find a suitable cap in the correct pressure range to suit the land rover radiator that will be compatible with an overflow tank.
As for losing all your coolant, well thats a mystery if you cannot see where it has gone. A standard holden 186 system holds approx 7 litres and with a land rover radiator you would probally gain another litre or more......so that's a lot of coolant not to be noticed!

Cheers, Mick.

Did you lose all of your coolant, or just what you could see? It could be air pockets in the engine that settle to the top when you are travelling. My Red motored Land Rovers had the LR radiator with the overflow bottle, but all my dad's Holdens didn't. Repco used to sell a kit for it, but haven't seen a genuine until later, Blue or Black motor perhaps.

Jeff

All good info!

Jeff, it lost the lot via the overflow. If you let it idle for a long time, you can see the water slowly rise but with no signs of engine compression feeding it (ie bubbles). I've had this happen on a venerable Mk 7 Jag & had the same symptoms ie when the rad cap was released, there was no sign of a pressuried system. I fixed it with a new cap.

The rubber seals on the caps I have are not what you would call supple so I'll try a new cap then investigate overflow tanks on the old Holden forums if that doesn't do it.

Hello Geodon,

I only have Series 3 Land Rovers not a 2A like yours. One of my Land Rovers has a Holden motor with a Land Rover radiator fitted. I also have a Series 3 original diesel motor and radiator - both radiators have overflow bottles fitted.

The Parts Catalogue has the the bottle showing as Part Number 564718. There is no mention of it being an optional part so it looks like they were a standard fitting. The steel cage the bottle fits into bolts on to the passenger side of the radiator and is part number 598531.

Kind Regards
Lionel

I have a '68 Toyota Crown Super Deluxe (super rare but similar age and systems for comparison) and have just rebuilt the engine and ancillaries in prep for a friends wedding. It originally had just the radiator with 13psi cap and overflow hose. After discussions with the rad rebuilder, we are using a lower pressure recovery cap on the radiator and have added a overflow tank to it with the original pressure cap.

The key is making sure that the rad cap is a recovery type (cap flow in both directions) rather than just straight pressure relief.

On the rover try a RRC tank, they are old style, metal and have a few mounts that can be bent to suit. But the key is cap pressures and types.