the CK78x is 19x34". That's the one I put in my K5. it's a 3 row. It's in the truck I'm selling, you can see it in the pics on my media page.
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CK5
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What radiators are good these days?
- Thread starter Thomas Fournier
- Start date
All the replacement I see listed are@19 x 29 or 31. That's a 3 to 4" difference
You are correct, I'm including the tanks. The core is 28.3" x 18.9" x 4.5". If you include the tanks, it's 33.9". They list it as a replacement for 78-86 gm c and k series.
https://www.mishimoto.com/gm-c-k-truck-x-line-performance-aluminum-radiator-78-86.html
Not sure why anyone wastes their time repro'ing the 17" radiators. Yeah, they were out there, not nearly as common as the 19" cores.
Not sure why anyone wastes their time repro'ing the 17" radiators. Yeah, they were out there, not nearly as common as the 19" cores.
Last night I measured a radiator I had built for a 77 k20 manual trans, a truck I no longer have. The core is 19x 31.
The measurements were such that it fit almost perfectly in place of the stock radiator. I put about a 1/2" under it, and had to bend the a/c lines a little where they go around to the front, other than that, it was an easy fit. And that was in a 90, they only say it fits up to '86. I don't think too much changed in terms of size, though. I would have had a lot more work trying to fit that Spectra in there, that's for sure. Interested in hearing why Mishimoto sent the smaller radiator in this case...they were the ones that recommended the CK78x to me, seems they would have done the same in this case.
86/87 is when the pick ups changed to Gmt400. the k5 and burb stayed square till 91. Prob why they limit to 86 model year.
Well i called Mishimoto and they are going to take the smaller one back and send me the 78x. Since i got back to them on monday they are going to give me the cyber Monday deal which was under $300!
I think the radiator size issue was an accident by myself and the rep i was talking too. They cleared it up thats for sure
The fit, finish and packing on the radiator was superb. it just ddnt fit my application. Ill update further when i get the big one. Should be here in the next few days.
I think the radiator size issue was an accident by myself and the rep i was talking too. They cleared it up thats for sure
The fit, finish and packing on the radiator was superb. it just ddnt fit my application. Ill update further when i get the big one. Should be here in the next few days.
Here is the update of the photos people! Sorry for the late response!
these photos are from the smaller radiator (oops)
these photos are from the smaller radiator (oops)
This is the proper "full-size" radiator that was installed. The older crappy looking one was the old one. It fit pretty good, but jot quite as tight as the old one...truck is at least 10 degrees cooler with the Mishimoto radiator.
while running it to fill it with antifreeze, the water inside the cap seemed to he "rushing" WAY harder than the old one. Not scientific but seems that way at least. Almost like the flow is much better.
while running it to fill it with antifreeze, the water inside the cap seemed to he "rushing" WAY harder than the old one. Not scientific but seems that way at least. Almost like the flow is much better.
Ned Kelly
1/2 ton status
Good pics. I like it. Where are these made?
I see you got a few fins bent, but that's not too bad considering it's the holidays. I've been waiting for a new exhaust manifold for three weeks...who knows why it's stalled in Rialto, CA. Glad it works for you, and like I said, mine looks like new inside and out and it's been almost 5 years....it's a quality product. Remember to check for voltage in there though, electrolysis will eat that thing up in no time if you have any wayward current floating around.
I had a really bad electrolysis issue back in the day so i put a bunch of grounds near and on the radiator and that was solved.
How do you check if there is electrolysis?
How do you check if there is electrolysis?
Hey, I'm sorry, I thought I had posted up and answer for this. I meant to, but I guess age is starting to take a toll. This is the method I've always used: Test for electrolysis using a voltmeter (DC scale). Place the positive lead of the meter in the engine coolant without touching the radiator sides. Clamp the negative lead on the battery ground.
For the test to be valid, there needs to be an electrical load. To get that load, first disable the engine so it does not start by pulling the coil wire.
Crank the engine over while reading the voltage in the coolant.
Next, start the engine and retest loading individual electrical circuits by turning off the lights, heater, air conditioning, etc.
With a cast-iron engine, the reading should be no more than 0.3 (3∕10) volt. A reading of 0.5 volts will destroy a cast-iron engine over time, and 0.15 volts will damage any aluminum component or engine.
If voltage is discovered, shut off one electrical load at a time until the reading drops to zero. Then, identify and fix the ground path for that component.
There are other ways I have read and seen used, but that seems to be the simplest for me. There is really no reason there should be voltage across the radiator/coolant, even a little. If there is, there are other issues, so try to get that reading to 0, it will probably save you some other trouble in the end.
Enjoy your new radiator!
.
For the test to be valid, there needs to be an electrical load. To get that load, first disable the engine so it does not start by pulling the coil wire.
Crank the engine over while reading the voltage in the coolant.
Next, start the engine and retest loading individual electrical circuits by turning off the lights, heater, air conditioning, etc.
With a cast-iron engine, the reading should be no more than 0.3 (3∕10) volt. A reading of 0.5 volts will destroy a cast-iron engine over time, and 0.15 volts will damage any aluminum component or engine.
If voltage is discovered, shut off one electrical load at a time until the reading drops to zero. Then, identify and fix the ground path for that component.
There are other ways I have read and seen used, but that seems to be the simplest for me. There is really no reason there should be voltage across the radiator/coolant, even a little. If there is, there are other issues, so try to get that reading to 0, it will probably save you some other trouble in the end.
Enjoy your new radiator!
.
bp71k5
3/4 ton status
I’ve had aluminum radiator issues for a while until I grounded a probe that touches the coolant. They would last for a month or two and then start weeping coolant from the core joints.
The probe is just a sacrificial anode, but I don’t think the anode is doing anything. It’s grounding the coolant that fixed the problem and I did a bunch of tests for the manufacturer to debug what was going on.
When I took a new radiator right out of the box and filled it with water, I could measure voltage from the coolant to the radiator body. Once I installed the radiator in the engine bay, I could measure .3V pretty quick and voltage would increase as the engine ran. Ron Davis mentions static buildup as a possible reason for that increase.
once the anode was installed in mine I obviously measure 0V in the coolant and the radiator has sealed fine for over a year. I even checked the anode after a year and it looks brand new without any sign of degradation. So I’m pretty convinced the coolant needs to be grounded or prevented from building up an electric charge in an aluminum radiator.
I need to test mine. That's not a lot of voltage for margin of error.
However, the coolant should be grounded, it touches the block. I find it hard to believe, but perhaps scale buildup in the block prevents it?
I believe I read somewhere that antifreeze is actually supposed to help with the stray voltage issue as well.
bp71k5
3/4 ton status
I also have a manual trans so there isn’t an oil cooler hookup to the radiator. If you have an auto, the cooler lines can act as a ground. That was the theory on why mine were failing. Went through a couple Griffens, and then a couple entropy radiators before entropy started to try and figure out what was going on.
No prof, I think Dex cool was developed for aluminum radiators.
wasted wages
1 ton status
Distilled water is a must.... depending on where you are in the country, you could have high mineral/ metals or TDS levels in tap water...
not 100% cure but it helps...
not 100% cure but it helps...
Good point, considering that TDS is technically a test of how conductive water is......
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