my jug runneth over

I have a 1995 D1, 138000 miles, This past august it developed a head gas leak. The heads were taken off and tested by a reputable machine shop, cleaned and die tested. L.R. gasket set was installed and all seamed well. Till this past week when I noticed there was no heat. My fist guess was a bad thermostat. I was right. It was stuck open. I replaced it with another, purged the air from the system (no swooshing ), the truck was not driven till today. After aprox. 3 miles all seemed fine, I stopped for fuel, checked the hoses and the overflow and it seemed as tho everything was working fine. I went another 2-3 miles to my destination. everything was still fine. After about 30 min.(the truck parked and off) I began the short journey home (5-6 miles). when I got out I smelled that sweet smell of coolant. so I raised the hood to find that the overflow tank had runneth over. The temp gauge never registered hot only normal. So I let it cool all the way checked the coolant and of course it was low. I refilled and tried another 5-6 miles and the same thing happened. What else could be causing this? the truck never got hot and was fine till of course the thermo went bad, but like I said before it stuck open.

I have checked all the spark plugs and none of them are wet, however even after a short time of the truck running the top rad hose feels as tho it is going to burst. Tomorrow I am going to replace the thermostat with another in the hopes that I may have gotten a faulty one to start with. If any one has any other ideas please let me know. Thanks.

Try it wihout the stat in and see if it still overheats or over pressurises.

Find the little connector and the temperature sender unit to make sure that they are connected together ... if not, then you won't get a reading on your gauge!

Keep us informed, and we can take it from there.

By the way, Landies are not trucks!!

Have you tried your expansion cap because if it cant hold the pressure in then it gonna leak from there, and if the pressure dont hold the water will boil.

sorry its a habit calling it a "truck". I have taken the thermostat out refilled and it does not overflow. I double checked all the connectors for the sensor/sender along with the wires to each. Without the thermo the temp gauge barely registers. Benjy I have three diferant caps and still got the same results before removing the thermo. After I removed the "new" thermo I put it in hot water (192 F) and it did open. The rad hose now feels normal ( based on the feel of my 98 4.0 after 15min of running).

A tip when changing thermostats is to put them in hot water before fitting them. That gets rid of any surplus gunge/lacquer which might have found its way into the seal and stuck it all together.

Hope your problem has now been resolved.

Please keep us informed.

Yes pretesting the thermostat is a great idea, and one that I do practice. However I am sorry as I may have misled you. I had thought that the thermo had became faulty after instillation so I removed it. I refilled coolant blah blah blah, and I am noe running Without a thermostat. I Rechecked the "new" thermo that I removed only to see if it was faulty, and it is not. Witch leads me to think there is something more sinister going on within the engine. But what?

Are you sure the water pump is ok sometimes replacing the head gasket can make the water pump fail it happened to my daughters car on the way home from the garage lol