disco 1 running hot and pushing water out of expansion tank

Oct 14, 2005
17
0
OK heres the problem, I bought this 94 disco with a bad engine, the PO ran it so hot back last summer it blew out the freeze plugs, ( HOT HOT) anyway I decided to buy another used engine, so I got one out of a wrecked in right front 95 disco in junk yard, with 155k miles on it, (nice looking rig and clean oil too) anyway I installed it in the 94 body and drove it 15 miles ( 45 to 50 degree day) and the temp started up 3/4 way on gauge and so i pull over and see coolant pushing out of radiator, so i let it cool a few minutes and went on my way, 15 miles later same thing happen but this time I turn on heater and it cools down, then coming back home it does it again, I can rev it up and it stops, so I pull out thermostat and replace with another and same deal , gets hot and overlflows etc, I pull out radiator and replace with Known good used one and same thing! im bleeding system too! so I take original radiator to shop and they said it was plugged up so they charged me $135 to clean and rod out radiator and I install and same thing if not worse now! its rad is cooler than the expansion tank, sometimes when its pushing water out of tank the gauge is half way even, im ready to give up, no water in oil and no oil in water, whats wrong with it? sometimes the heater stops putting out heat too! seems like air is getting in it from somewhere, exzaust isnt smoking or steaming either! im at wits end, its usually doenst get but 3/4 way up on gauge and then cools back down, fan is turning and feels OK too! its now doing this even in 20 degree weather too! Help!
 
Apr 20, 2004
6,926
223
Floyd, Virginia
check the actual reading with a thermometer and see if its really hot... also...are you bleeding it after installatin of all the new additions?....hows the waterpump feel on the front? does the vc work as should? are you losing coolant?....can you smell coolant inside the truck? check where the heater core runs through the firewall and see if it got bumper during the engine install.

if all this stuff above checks out...run a compression test
 
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barefoot

Guest
are you bleeding it with the front end raised, heater on high and caps off?
 
Oct 14, 2005
17
0
Ive bought over 100 dollars worh of anitfreeze in the past 2 weeks, I had 2 radiators in it and acutally had both them rodded out and yes I bleed the system with front end up and caps off, it runs cool for like 15 minutes and then driving it at road speed it starts to climb the temp gauge, when I pull over I can rev engine up and gauge falls down quick then I look at water bottle and its overflowing and temp is cool on gauge, also I notice when I turn engine off during this I can hear it boiling in the expansion tank, it seems to boil in the heater core too! sometimes the heater core will not put out any heat and other times its hot as can be, engine runs great and came out of a wrecked disco with no over heat problems so I dont know whats wrong with it , im going to try taking out thermostat and bleeding one more time before I take heads off.
 
C

Canadian_Zuk

Guest
I hate to say it, but it sounds like a head gasket to me.
 

singingcamel

Well-known member
i would say its could be a head gasket ,but more than likely its a slipped sleeve, cracked block, best thing to do is to remove the heads and peak, unfortunately its a pain to diagnois without removing the heads.
these 3.9 l are notorius for slipping sleeves..good luck
 

Ed Cheung

Well-known member
Aug 23, 2006
1,584
2
Hong Kong
That's what happened to me on Sat., I ended up with white smoke comming out of my tail pipe, I'll be taking out the head to change the head gasket very soon.
To be honest lots of things can go wrong with the cooling system to make it boil the coolant, bad thermostat, bad gasket cannot whole the pressure, block radiator, as a result of cannot hold the pressure in the system, the coolant start boiling creating air pockets, which makes things worst really quick.
If you already got the radiator and thermostat taken care of, why not take one more step to crack open the engine to exam the head gasket, the heads, and cylinder liner so you can get it over with.
For the past 6 months, my truck had been lossing coolant, needle move up 3/4 once a while, I just kept puting off the repair. Now I really need to sort it out (see my other post).
 
Oct 14, 2005
17
0
The strange thing is that the radiator isnt hot when the coolant is over flowing boiling, also if you run the heater all the time it usually doesnt run hot on the gauge as often. no white smoke either and no large bubbles in tank when I first start it up either in the morning . do head gaskets deteriate from sitting? po of wrecked engine didnt have any problems with it beore he wrecked but it sat in a salvage yard in vehicle for 2 years before I installed it in my rover
 

tikicar

Well-known member
Oct 24, 2006
57
0
York, Pa.
You still have air in the system. Anytime you have heat then loose heat it is because there is no water in the heater core when you have lost heat. Meaning air in there. Try to rebleed the system. It should have the little plug in the heater line next to the plenum to undo to release air also. Also why radiator is cool. Sounds like air. Now you might have air getting into the system from an internal leak like head gasket. But try to rebleed the system again. Scott 97XD
 

jhelton001

Well-known member
Jul 20, 2005
106
0
I had this same problem with a Nissan Sentra. I did every thing you mentioned above it turned out the water pump impeller corroded and separated from the shaft. Before you do anything else pull the pump and inspect it. I could not have described better what you list above when this happened to me and bet this is your problem.
 

singingcamel

Well-known member
littleeuroimport said:
The strange thing is that the radiator isnt hot when the coolant is over flowing boiling, also if you run the heater all the time it usually doesnt run hot on the gauge as often. no white smoke either and no large bubbles in tank when I first start it up either in the morning . do head gaskets deteriate from sitting? po of wrecked engine didnt have any problems with it beore he wrecked but it sat in a salvage yard in vehicle for 2 years before I installed it in my rover


thats because your pressurizing your system due to slipped sleeve or cracked block
 
B

barefoot

Guest
the previous owner may not have said anything so he could get the highest dollar possible or maybe he just didnt know yet or maybe the gaskets blew because of the wreck. either way, sounds like a gasket allowing air in since you are sure you are bleeding correctly. like stated above, you will need to pull the heads. i guess it could also be a liner but most of the time, i understand, they make noise.

as far as you saying that the expansion tank is boiling while the radiator is not hot....this points more at a gasket failure because the coolant is not actally boiling but it is air pressure bubbling out! check it with your gun, its prob no where near bioling temp....

enjoy!
 
Oct 14, 2005
17
0
For whats its worth guys I pulled out the thermostat and ran it with out one and all the over heating problems went away! Ive driven it many miles since then and no problems, it usually runs way below half way when fully warm and outside temp is 50 degrees so I think it may have been 2 bad thermostats? Im leaving that thing out for now! just wanted to tell everyone what I did! thanks
 

Phillip Lehn

Well-known member
Dec 11, 2005
91
0
59
Sydney
Yep. That has happened to me. The thermostat had closed in a middle of a long trip and i often change the coolant with anti corrosion.. Lucky for me I had a temperature alarm as I don`t look at the guages every 5 minutes. I pulled the guts out of the thermostat and put it back in until I installed a new one. Its the first one that had played up on me.
Phil