Normal temperature but all of a sudden when stoped blew out a gallon of coolant

Jay G

Member
Aug 26, 2021
5
0
Gloucester Ma
Hi
I am new to this forum. I have always repaired my vehicles from the late sixties to the present.I had 1962 defender and a 1971 defender.Now after all these years I picked up a 1997 disco in nice shape with cosmetic, minor wiring issues and a wheel bearing that needed changing. On the first run on the hottest day this week high 90's I dove it for about five miles watching the temp gauge and all was great just below half. I pull into a parking spot and a guy in front on the sidewalk looks down and points to the front of the disco. I get out and he say's just as you stopped you must have blown a hose all of a sudden it hemorrhaged coolant. It lost a little over a gallon. All this time no steam no leaks no indication of trouble. I let it cool then I started the engine and slowly added room temp water until it was full. No leaks or any indication of problems so I drove it home about six miles still hot as heck out and no problems or leaks. I NEVER saw anything like this in my life. I haven't burped it yet or looked deeper into what happened yet so I thought someone could save me some time and frustration if this happened to someone else.Thanks for reading.
 

Toran

Well-known member
Feb 3, 2017
347
31
Ohio
Could be a clogged radiator.
Make sure your coolant reservoir cap has a good seal. I had the same issue a couple years ago and turned out it was a pin size hole in the coolant reservoir that was causing the overflow when I would turn the truck off.

Also make sure your clutch fan is working.
Make sure your two condenser fans are working when you have the AC on.
 

Tugela

Well-known member
May 21, 2007
4,484
298
Seattle
I dove it for about five miles watching the temp gauge and all was great just below half.

An important piece of missing information here is that the dash temp gauge is an imprecise instrument. It is effectively a three-state gauge:
1. Engine is cold
2. Engine is fine
3. Engine is fucked

If you connect a reader to your OBD-2 port and watch live data of your engine coolant temps, you'll see that temperatures can swing by 50 degrees or more while the dash gauge stays rock steady at center. I think the highest I've seen on a data reader is 220F while the gauge needle was just below half, others may have even higher observations.

Bottom line - if you want a more precise idea of what your engine coolant temps are, monitor them with an OBD-2 data reader. A popular combination is a Bluetooth OBD-2 dongle (like the OBD Link X) paired to a mobile device running the Torque app. Other options will also work.
 
Aug 20, 2007
2,684
29
Nashville TN
Ultra gauge all the way. Makes me feel so much better. I know exactly what temperate range my engine should be at idle, speed, and under 50mph whether in 30F or 100F weather. You learn the truck and can start to catch issues before they prove catastrophic once you know the range of temperatures and what scenarios to expect them in.
 

Jay G

Member
Aug 26, 2021
5
0
Gloucester Ma
All good suggestions. I will start first with burping the system and then checking the things everyone suggested. I did wonder if the temp sensor was ok or malfunctioning giving a false reading. I am also going to tap onto one of the small coolant lines with a t and run a line with a pressure gauge to see what the pressure is in the system as I am driving.Thanks everyone I will post the results if and or when I find the culprit.:)
 

discostew

Well-known member
Sep 14, 2010
6,373
477
Northern Illinois
These radiators rot out. If you look at the backside of the radiator thru the fan you can see it. All the corrogated cooling fins will be gone and only the tubes remain.
Also make sure the belt is routed properly. You should be able to google that.
Then make sure your fan doesn’t wobble on the shaft.
And I suppose if it’s been sitting for a long time the thermostat could be stuck closed.
 

Jay G

Member
Aug 26, 2021
5
0
Gloucester Ma
All good suggestions. I will start first with burping the system and then checking the things everyone suggested. I did wonder if the temp sensor was ok or malfunctioning giving a false reading. I am also going to tap onto one of the small coolant lines with a t and run a line with a pressure gauge to see what the pressure is in the system as I am driving.Thanks everyone I will post the results if and or when I find the culprit.:)
OK I monitored the temp with my live data and the gauge and sender are good running about 175 idling for about an hour. Cap tight no leaks no drips. Shut it down worked on something else for about an hour. Start it up get ready to go downtown and all of a sudden coolant starts dripping from the seam on the overflow tank. Sealed it for now ordered a new tank and will leave the cap slightly loose not to build pressure and should be good till the new tank gets here Saturday.Thanks for the help
 

Tugela

Well-known member
May 21, 2007
4,484
298
Seattle
Hope that's the solution. I heard about the failures of the stock black plastic coolant reservoir and switched to the clear plastic one as a pre-emptive measure. Just curious which version yours was. If your radiator is still the original it might be worth planning a replacement.
 

MNinWI

Well-known member
Dec 19, 2007
82
2
To reinforce what Tugela said, yes the gauge only reads three positions. You assume because it is a gauge with a needle that the needle will fluctuate with temperature, but not so. I was quite surprised a few times to notice my gauge moving rapidly up from cold to mid position during a few seconds as the temperature rose to whatever temperature threshold was reached to cause the needle to move. And once in the mid position, even when the temperature fluctuates, the needle stays right there with no movement.

I assume that the gauge will also show a high temp, but fortunately I have not learned if that occurs or not on mine. Mine is a 2003 D2
 

Jay G

Member
Aug 26, 2021
5
0
Gloucester Ma
All is good now it turned out to be an intermittent tank leak. Got a new clear one and no leaks or loss of coolant now. Thanks for the tips.
 

Swedjen2

Well-known member
Sep 12, 2018
552
111
California
All is good now it turned out to be an intermittent tank leak. Got a new clear one and no leaks or loss of coolant now. Thanks for the tips.
Do you mean clear as in a Pepsi bottle clear? Or opaque yellow? With respect to Tugela, the clear ones are questionable from what I've read.
I just read where someone else just bought and aluminum tank for $167 from Allisport in the U.K. Finest quality. The welding was artwork.
The other problem with the plastic tanks are the small inlet/outlet nipples. I was losing coolant and discovered the one below the cap had a hairline crack where is joined the main body. It didn't leak until the pressure built up.
I think it was the throttle heater body return line didn't line up exactly and was imparting a "bending moment" on the plastic joint that exceeded the material or ultimate strength. The temperature cycling doesn't help either.
Just make sure the product(s) you buy don't originate in the PRC. Sadness and regret will surely follow.
 
Last edited:

Jay G

Member
Aug 26, 2021
5
0
Gloucester Ma
Do you mean clear as in a Pepsi bottle clear? Or opaque yellow? With respect to Tugela, the clear ones are questionable from what I've read.
I just read where someone else just bought and aluminum tank for $167 from Allisport in the U.K. Finest quality. The welding was artwork.
The other problem with the plastic tanks are the small inlet/outlet nipples. I was losing coolant and discovered the one below the cap had a hairline crack where is joined the main body. It didn't leak until the pressure built up.
I think it was the throttle heater body return line didn't line up exactly and was imparting a "bending moment" on the plastic joint that exceeded the material or ultimate strength. The temperature cycling doesn't help either.
Just make sure the product(s) you buy don't originate in the PRC. Sadness and regret will surely follow.
opaque
 

FatMcNasty

Well-known member
Mar 28, 2006
187
43
Southern Oregon
Do you mean clear as in a Pepsi bottle clear? Or opaque yellow? With respect to Tugela, the clear ones are questionable from what I've read.
I just read where someone else just bought and aluminum tank for $167 from Allisport in the U.K. Finest quality. The welding was artwork.
The other problem with the plastic tanks are the small inlet/outlet nipples. I was losing coolant and discovered the one below the cap had a hairline crack where is joined the main body. It didn't leak until the pressure built up.
I think it was the throttle heater body return line didn't line up exactly and was imparting a "bending moment" on the plastic joint that exceeded the material or ultimate strength. The temperature cycling doesn't help either.
Just make sure the product(s) you buy don't originate in the PRC. Sadness and regret will surely follow.
that would be me that bought that beautiful aluminum tank. :)
 
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