Beating an overheated horse

Frobisher

Well-known member
Dec 27, 2012
200
68
Pennsylvania
Granted, engine over heating (roverheating?) has been bandied about ad nauseum over the years, but now I'm faced with a weird puzzle I can't quite sort out.

My 95 Disco overheated quite unexpectedly on the 4 mile drive to work in 40º weather last week. It's typically "warm" in the cab after 3 miles and when it wasn't, I was a bit surprised. I noticed it going up a short hill and then I saw my temperature gauge (factory, nothing fancy) pegged in the red. I pull over to let it cool, check the coolant reservoir, and it's empty. I had coolant sprayed all over the right side of the engine and pooling in the indent on top of the reservoir. Weird.

I had just checked my coolant two days before and it had been holding steady for months, and now this. I crept it the half mile to work, parked it and mulled it over during the day. I topped it off with coolant at the end of the day and started home. I blew white smoke all the way home, overheated on the same hill (uphill both ways) but made it home with coolant in the tank. Never saw a puddle in the driveway or parking lot.

Compression test showed at least one bad cylinder, so I spent the weekend replacing the head gasket and thermostat - almost 3 years to the month from the last one. I keep a pretty good eye on the fluids, so this was a surprise. After buttoning it all up, I took a short drive around the block - more white smoke out the tailpipe and now all over coming out the hood. Let it cool off, pressure tested the system and found it leaking at the connection to the heater core. And by leaking, I mean pouring into the footwell on the passenger side. So that explained the spraying in the engine bay I found earlier.

I bypassed the heater core and tried it again. Good on the casual drive, but when I gassed it hard on a straightaway, the temperature went straight up then back down when I let off. I was still puffing bits of white smoke, but I'm hoping it was just burning off coolant in the cats. The temperature spikes may have been air bubbles, but it seemed too tied to the acceleration to be that simple. No leaks in the engine bay and pressure holds in the system.

Peter's comments on the link below have led me to ask about this as it came about as a surprise, and now I'm stuck.


For details, I have a clean Nissens rad from 3 years ago, water pump (used but good from Paul Grant) that has 21K known miles, with no leakage, also no leakage on the hoses, but my fan clutch may be dying. I tried a few fans from my buddy but they didn't prove to be any better. Before I sell or part this out, I want to give it one more try with a new Chevy fan clutch. My current Chevy clutch is somewhere between 5 and 8 years old, but I need to check my log.

Any possible suggestions on this? I know there aren't a lot of parts to the Disco cooling system, so I'm flummoxed on what to do next. Thanks in advance.
 

Frobisher

Well-known member
Dec 27, 2012
200
68
Pennsylvania
I did both head gaskets 3 years ago and then a repeat this weekend. Didn't think about a leak down test. Maybe if there’s a next time.
 

DarylJ

Well-known member
Apr 3, 2011
440
24
Doylestown, PA
Also, I'm really convinced that a lot of these trucks simply don't have the cooling system bled properly.

I've vacuum bled things with a seemingly correct coolant level and just watch bubbles come up and have to put in half a gallon to get it back to the correct level. That's enough to have elevated temperatures and enough to start blowing head gaskets. Not like that's hard to do on these things.
 
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lunchbox

Well-known member
Apr 20, 2004
2,133
165
50
St Louis, MO
Every cooling issue I’ve had was due to improper bleeding. It can take a solid 30 minutes to bleed if, depending on the weather.

remove both fill caps
fill with fluid
start truck
crank the heat
walk away, read a book, send mean texts to Todd, walk the dog, etc…
check level after bubbles are gone
only fill at the radiator, never the tank
 

Frobisher

Well-known member
Dec 27, 2012
200
68
Pennsylvania
Yeah, I’m starting to think more about the burping. I’ve done it several times with no issues in the past, and I think we cut the corner a little this time in haste. I’ll work around the disconnected heater core, but I am a little curious. The white smoke on test drive kind of threw me off a bit, but it seemed to get a little better after a bit. Mostly.

If only it weren’t parked an hour away.
 

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
Yeah, I’m starting to think more about the burping. I’ve done it several times with no issues in the past, and I think we cut the corner a little this time in haste. I’ll work around the disconnected heater core, but I am a little curious. The white smoke on test drive kind of threw me off a bit, but it seemed to get a little better after a bit. Mostly.

If only it weren’t parked an hour away.
It could be that coolant was dripping off the corner of the block while the head was off. It can go right into the open exhaust pipe.
As far as filling it. Like these guys said, take the plug out of the top of the radiator and fill the reservoir. It will come out the hole in the top of the radiator when it’s full. That hole in the top of the radiator is the best way to empty the cooling system without making a mess. I sink a rubber hose to the bottom of the radiator and syphon it into a pan.
 
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robertf

Well-known member
Jan 22, 2006
4,780
355
-
I vote radiator


99 d1. bought as a junker. even after 2 years I wasn't convinced the block wasn't cracked. It was fine in winter with the occasional spike to 220 while driving on the highway. Summer it overheated almost instantly when the AC was on or when traffic stopped.

It got warm a few weeks ago and the problem resurfaced. Ive thrown a flowkooler waterpump, alisport reservoir, and every fan clutch I could find at it.


Finally I replaced the nissens I put in when I got it running with a recored brass. problem mostly solved. It still seems to run away temp up to 205 (thats when I shut it off) when idling with the AC on for longer than 30 minutes. probably fan clutch. Ill just live with it for now.

probably not the nissens fault directly. I also put a coolant filter in it maybe a year ago and have captured about a cup full of trash before the recore went in. Rust, sand, possible block sealer. Recored radiator wasnt exposed to that
 

Tugela

Well-known member
May 21, 2007
4,754
562
Seattle
I installed a Nissens in my D1 in 2017 as part of a comprehensive cooling system replacement. It worked really well for about four years, then last summer I took a multi-day off-road trip with 5,000-foot climbs in triple digit air temps and the radiator struggled. Swapped in a 4-row, all-aluminum radiator last fall and coolant temps are back where I want them. Vacuum bled the cooling system after installing the new radiator.

IMG_20220729_174151856_HDR.jpg
 
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robertf

Well-known member
Jan 22, 2006
4,780
355
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different truck, but I tried an aluminum 4 row from amazon. it was complete junk. ordered one from ali to replace it. much nicer. hope to install it this his weekend
 

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terryjm1

Well-known member
Jan 23, 2011
1,486
375
different truck, but I tried an aluminum 4 row from amazon. it was complete junk. ordered one from ali to replace it. much nicer. hope to install it this his weekend
Curious, what were the issues with the Amazon radiator?
 

robertf

Well-known member
Jan 22, 2006
4,780
355
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biggest issue was it had a massive coolant leak, but aside from that...

-the bottom plate was too wide. It didnt clear the steering box mounts on the frame as shown in the picture

-the return hose was welded at the wrong angle, fan shroud would have had to be mutilated to clear

-oil and trans lines didnt have the correct o-ring bore and the threads were bad


-i didnt like the proprietary thread they used on the fill port
 

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terryjm1

Well-known member
Jan 23, 2011
1,486
375
biggest issue was it had a massive coolant leak, but aside from that...

-the bottom plate was too wide. It didnt clear the steering box mounts on the frame as shown in the picture

-the return hose was welded at the wrong angle, fan shroud would have had to be mutilated to clear

-oil and trans lines didnt have the correct o-ring bore and the threads were bad


-i didnt like the proprietary thread they used on the fill port
That is real bummer.
 

Frobisher

Well-known member
Dec 27, 2012
200
68
Pennsylvania
Thanks for all the responses. As it turns out, I seem to have a cracked block based on a combustion leak test. That's some pretty cool chemistry, and it didn't take long to say "You're engine is stuffed."

Now, to figure out what to do about parting or selling it since I have a 109 waiting in the wings to get built. No more time and money on the Disco. Drat.
 

pinkytoe69

Well-known member
Jan 14, 2012
1,689
182
minnesota
Thanks for all the responses. As it turns out, I seem to have a cracked block based on a combustion leak test. That's some pretty cool chemistry, and it didn't take long to say "You're engine is stuffed."

Now, to figure out what to do about parting or selling it since I have a 109 waiting in the wings to get built. No more time and money on the Disco. Drat.

Toss some irontite block sealer in it and see what happens.

https://irontite.com/p/8191-ceramic-seal-pint/v/8191

I got almost 40k out of a cracked '04 4.6 block before a head stud popped its threads. Those are total garbage compared to a 95 I would think, so what the hell?

If it doesn't work you're only out 20 bucks and maybe a radiator 😄
 

DiscoClay

Well-known member
Mar 18, 2021
433
84
Chapel Hill, North Carolina, USA
It got warm a few weeks ago and the problem resurfaced. Ive thrown a flowkooler waterpump, alisport reservoir, and every fan clutch I could find at it.

I also put a coolant filter in it maybe a year ago and have captured about a cup full of trash before the recore went in.
- How are you liking that flowkooler? I am just getting ready to order one.

- Can you describe your coolant filter, brand, installation, etc? I am looking into one as well.

I often wonder why people don't go for copper more often.. Aluminum needs to be as pure (and soft) as possible (e.g. 1050, 1060), to conduct heat well; around a 1/3 to a 1/2 better (again, this is from ancient memory). Brass is way worse than high purity/low-silicon aluminum...like almost half as good. But the alloy types and how/if they are annealed makes a *huge* difference.

Do not buy an aluminum radiator if you do not know for certain the alloy and treatment (e.g.: annealed) of it. I would not use brass for anything other than the tanks. Copper is by far the best radiator material.. even crappy copper. Think of it like this: Copper is ~half better than Aluminum is ~half better than brass (your results may very vary).

Also, all things being equal, a larger area with fewer cores will cool better than a smaller area with more cores. I know we have a fixed cross-section to deal with, so this is somewhat academic, but I recall using fewer cores with a high volume pump and getting better heat extraction, the main application was a BMW road racer but we applied the understanding to our turbo street cars; there were likely several other factors but it's been a long time :p
 

StangGT5

Well-known member
Feb 4, 2019
295
130
Atlanta, GA
- How are you liking that flowkooler? I am just getting ready to order one.

- Can you describe your coolant filter, brand, installation, etc? I am looking into one as well.

I often wonder why people don't go for copper more often.. Aluminum needs to be as pure (and soft) as possible (e.g. 1050, 1060), to conduct heat well; around a 1/3 to a 1/2 better (again, this is from ancient memory). Brass is way worse than high purity/low-silicon aluminum...like almost half as good. But the alloy types and how/if they are annealed makes a *huge* difference.

Do not buy an aluminum radiator if you do not know for certain the alloy and treatment (e.g.: annealed) of it. I would not use brass for anything other than the tanks. Copper is by far the best radiator material.. even crappy copper. Think of it like this: Copper is ~half better than Aluminum is ~half better than brass (your results may very vary).

Also, all things being equal, a larger area with fewer cores will cool better than a smaller area with more cores. I know we have a fixed cross-section to deal with, so this is somewhat academic, but I recall using fewer cores with a high volume pump and getting better heat extraction, the main application was a BMW road racer but we applied the understanding to our turbo street cars; there were likely several other factors but it's been a long time :p
I think OP's Disco is long gone.

As one last kick on the dead horse, a new decent aluminum radiator is way better than a 25 year old copper one. The cost of restoring a copper unit isn't cheap either.

Not to jinx myself, but I have swapped a myriad of aluminum radiators in Rovers with consistent results. I've also seen a couple doughy pot aluminum ones for Jeeps. Some Chinese make impressive (for the cost) units, others you wonder why they even put it on a boat.
 
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