Mishimoto Aluminum Radiator

jpowel29

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Feb 1, 2008
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Started noticing a few spots of coolant under the front of the truck earlier in the fall (thought at the time the lower rad hose was not sealing to the rad outlet). Pulled the truck out of service to re-paint it and finally tore into the front of the truck to find my Mishimoto Aluminum Radiator leaking from what looks like both sides. Bought it new 4 years ago but it has maybe 30k miles total on it. Always kept fresh coolant in it. Anyone else have one go bad? I also run their intercooler (which is built like a tank). Both look very well built so I'm surprised to see a service failure.
 

c20elephant

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Apr 25, 2013
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4 years not too bad considering how rough the front end rides. May want to take a close look at the intercooler/radiator mounting rubber isolators and the core support bushings. Mishimoto will send ya a new one for a $100.00 life time warranty fee for shipping from what I have read in the past...
 

THEFERMANATOR

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Feb 16, 2009
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If you do a google search, you'll find electrolisis seems to be an issue on them. Not just the duramax models, but alot of them have issues. From what I've found, they have them built oversees, hence how they can afford to sell them for less than the others. Theres a thread over at duramax forum where they had the guy put in new cab bushings and all kinds of stuff. I find that odd since the radiator in these trucks is not supported by the truck, but instead rides solely on the intercooler, and in turn the intercooler is mounted to the truck. So if you're going to have trouble, the intercooler should long before the radiator.
 

Mike L.

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Aug 12, 2006
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Ferman, should a ground be added to the radiator.?

The radiator should never be grounded. I think that would make matters worse. I think grounds should be battery to engine and chassis and body to chassis and engine. Probably better to isolate radiator with rubber insolation from any metal contact.
 

THEFERMANATOR

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I'm waiting for the chinese knock off ones to come back in stock. They had em on amazon for $155 with free shipping, needless to say they sold out QUICK! As to grounding, mishimoto has told several to run a ground straight to the battery negative to try and control electrolisis. I want one so I can reroute my heater core return to the radiator for the front heater to take care of an issue I'veencountered twice now. Going down a 6-7% grade when it's cool out and the stats close so you lose luquid cooling through the radiator, but you can only go 30-35, so you don't get good enough air flow across the external cooler to keep temps in check. After 3 miles or so, trans temps spike up to 250+, and you hit hot trans mode. Trans temps cool off as soon as you get back on it and the stat opens, but I don't like the high temps during those situations. In years past GM ran the heater core return just above the radiators trans cooler just so that didn't happen(and also to help warm the trans up quicker when it's cold out).
 

Chevy1925

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Oct 21, 2009
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I'm waiting for the chinese knock off ones to come back in stock. They had em on amazon for $155 with free shipping, needless to say they sold out QUICK! As to grounding, mishimoto has told several to run a ground straight to the battery negative to try and control electrolisis. I want one so I can reroute my heater core return to the radiator for the front heater to take care of an issue I'veencountered twice now. Going down a 6-7% grade when it's cool out and the stats close so you lose luquid cooling through the radiator, but you can only go 30-35, so you don't get good enough air flow across the external cooler to keep temps in check. After 3 miles or so, trans temps spike up to 250+, and you hit hot trans mode. Trans temps cool off as soon as you get back on it and the stat opens, but I don't like the high temps during those situations. In years past GM ran the heater core return just above the radiators trans cooler just so that didn't happen(and also to help warm the trans up quicker when it's cold out).

That explains my hot tras issue i had coming down some steep grades this past summer while towing. i was down around those speeds and that damn trans temp started climbing fast!!! scared me pretty good. i would figure the bypass tube on the water pump would be enough but seems not
 

DrtyMax07

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Dec 12, 2008
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I had the same problem with a Mishimoto radiator. First one started leaking about 2 weeks after installed. They sent me a new one with no questions asked. After about another week or 2 it started leaking. This time I sent it off to a radiator repair shop and they determined it was due to electrolisis. I tried ground straps and even coolant additives with no help. Stock one back in now and no problems since.
 

c20elephant

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Apr 25, 2013
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These link have some good information about grounding-vs.-not grounding the radiator and a few other explanations of what electrolysis is and is not. Some say ground some say do not and an anode would be best, with an anode you need an additional bung in the radiator. You might have electrical issues with your truck or the coolant is weak....

http://forums.corral.net/forums/gen...reventing-electrolysis-aluminum-radiator.html


https://forums.nasioc.com/forums/showthread.php?t=2442729


http://www.pirate4x4.com/forum/jeep-non-hardcore/991866-grounding-radiator.html#post13103442


http://www.pirate4x4.com/forum/13103442-post15.html


http://asecertificationtraining.com/testing-for-galvanic-activity-and-electrolysis/
 
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THEFERMANATOR

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That explains my hot tras issue i had coming down some steep grades this past summer while towing. i was down around those speeds and that damn trans temp started climbing fast!!! scared me pretty good. i would figure the bypass tube on the water pump would be enough but seems not

Problem is theres no coolant flow through the passenger side radiator end tank until the t stat opens. On most every other truck GM returned the heater core flow to the radiator to keep flow across the cooler. With the LS engines and duramax, they stopped doing it. Freaked me out to the 1st time, 2nd time doing that pass I speed up some, and kept temps down. The wife didn't much care for going that fast, but I didn't feel like going into overheat again.
 

Chevy1925

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Oct 21, 2009
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Problem is theres no coolant flow through the passenger side radiator end tank until the t stat opens. On most every other truck GM returned the heater core flow to the radiator to keep flow across the cooler. With the LS engines and duramax, they stopped doing it. Freaked me out to the 1st time, 2nd time doing that pass I speed up some, and kept temps down. The wife didn't much care for going that fast, but I didn't feel like going into overheat again.

ah i see. thanks ferm :D
 

IdahoRob

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Jun 5, 2007
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We stopped selling their products well over a year ago. Over 30% failure rate within the first year of purchase on the radiators and intercoolers, some instantly. They do not work with the installer nor do they warranty installation or shipping.

This is not an electrolysis issue on the ones that I have seen, this is poor welds and cracking tanks/welds.

So we are still replacing their products on trucks and eating the labor, coolant and shipping. We have customers that are on their third replacement.

Should give you a good idea that they don't care when they never want the old product back for R & D.

In my opinion, I'd stay away.
 

Awenta

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Sep 28, 2014
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We stopped selling their products well over a year ago. Over 30% failure rate within the first year of purchase on the radiators and intercoolers, some instantly. They do not work with the installer nor do they warranty installation or shipping.



This is not an electrolysis issue on the ones that I have seen, this is poor welds and cracking tanks/welds.



So we are still replacing their products on trucks and eating the labor, coolant and shipping. We have customers that are on their third replacement.



Should give you a good idea that they don't care when they never want the old product back for R & D.



In my opinion, I'd stay away.



What are you using now? Anything besides oem.

I might try to squeeze an lbz cooling stack in


Sent from my iPhone using Tapatalk
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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We stopped selling their products well over a year ago. Over 30% failure rate within the first year of purchase on the radiators and intercoolers, some instantly. They do not work with the installer nor do they warranty installation or shipping.

This is not an electrolysis issue on the ones that I have seen, this is poor welds and cracking tanks/welds.

So we are still replacing their products on trucks and eating the labor, coolant and shipping. We have customers that are on their third replacement.

Should give you a good idea that they don't care when they never want the old product back for R & D.

In my opinion, I'd stay away.
I read on some other boards that they were having them built in Japan, then they started getting ALOT more failures, and it was rumored that they had switched to China for production(these were in MUSTANGS). They probably don't want them back because they're just reselling overseas stuff.
 

06DDLBZ

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Mar 13, 2017
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My truck was wrecked by my wife and had both their intercooler and radiator. The truck was almost done and I had to wait six weeks maybe eight weeks on the backorder. The truck flooded while waiting on this part so I have so animosity towards Mishimoto now. I am sure this is when they switched manufacturing plants. Makes me wonder where this POS of came from now.

What about their intercooler?