I had the Local Radman replace my heater core on my 99-3.8 and it lasted for abought 8 months the 2nd one lasted for abought the same time. The guy that is doing the work seems to know what he is doing. How dificult is it to replace this dam heater core. I would like to give it a shot. Thanks

Id be curious to know why they keep failing? Are they clogging up or what? There isnt a tremendous amount that can go wrong with a heater core unless it clogs or starts to leak.

with the Canadian Dollar worth more it would OK to splurge and buy a Modine heater core. (the GM unit seems to work good also)

You car was an overheater: I am assuming you already got rid of the Dex; How hot does your heater get? -Does it burn you or just get warm?

The 3.5L is aluminum and dissipates heat well. The 3.8 is iron and builds up heat which is why you externally fanned it, and I thought you had a LX5 overheater (Winter usually)

My 99-3.8 did always overheat I could not solve the problem, I replaced the temp sensor that did not help, I did notice the cooling fans were not comming on eventhough the temgauge was at least a 1/4-inch above the half point on the temp gauge. To correct the high temp I installed a cooling harness that makes the rad cooling fans run all the time and a new 192 stat, That solved the overheating and yes I did go to green coolant and the heater cores were still blowing. The car is in the shop getting a new core installed the installer is going to try a different manufacturer eventhough he had no problems with his current supplier. I hope this one works out.

go universal coolant and add an additive like "water wetter" to it. You need solutions to keep your car under the 1/2 heat mark.

Go synthetic oil also. Mobile1.

Doesn't the tranny cool thru the radiator also? -How does your tranny run. A tranny with a bad pump could be heating up your radiator also.

Are they rebuilds? Dirty solder or there are way too many (tube) cracks in that standard core is buy a new one or make sure they are new going in.

The heater core were all new the ate all made of aluminum. I just think they are aftermarket junk there seems to be 3 levels of aftermarket junk in the market Junk, real bad Junk and ultra junk. thanks to chiness cheap manufacturing and bad copies.

I like Napa because they usually have 5-6 levels of junk and some of their junk is a actually quite good junk = they have a better selection.

RockAuto is actually quite good also for selection.

I like Napa because they usually have 5-6 levels of junk and some of their junk is a actually quite good junk = they have a better selection.

RockAuto is actually quite good also for selection.

Thanks for your suggestions I am having it done under warranty, the shop calls the shots on what they use, the last one only lasted 5 months, hope this one will last a few years.

Ok I am on my 3rd heater core hopefuly this will last. The rad guy told me the last heater core he used was an oem part

Three heater core failures does seem odd. Do you think the failures can be tied to the modifications you made to the cooling fans? Unfortunately, i don't know enough about cars but it seems to me that the modification you made could be related to these failures.

I can appreciate what everyone is saying about aftermarket parts but no company has stayed in business making bad parts. I don't see how an after market heater core would go defective so fast. Plus I doubt a good mechanic will buy parts from a bad company.

Sounds like he did that after the heater core started blowing.

Doubt it's the radiator cap not blowing off at 15 psi. Have you replaced the radi cap or had it pressure tested?

Could be the case but I doubt it is the part. Not much to heater cores.

It seems there are a couple of solutions floating around on the internet regarding the overheating: replacing the radiator cap and plastic air dam under the front end of the car.

I hope he finds a solution.

Guys note I solved the over-heating problem with the installation of the wiring harness, I did this after I blew the orginal heater core. The temp does not go above the half point. The rad cap I think is 15-lbs, I blew the 1st replacement after 10 months (aftermarket unit)2nd replacement blew after 6-months ( OEM GM unit) I hope the 3rd unit lasts ( aftermarket unit) Note: the Rad guy said he has never had problems with his aftermarket units

I'd be looking for stray voltage getting into the cooling system, this can eat up heater cores but usually takes longer, put a voltmeter on low scale, one end in the coolant/radiator, ground the other lead, if the voltage is more than .25v there is a problem.

I'd be looking for stray voltage getting into the cooling system, this can eat up heater cores but usually takes longer, put a voltmeter on low scale, one end in the coolant/radiator, ground the other lead, if the voltage is more than .25v there is a problem.

I will give it a try. thanks

An Update I drained the rad and found a lot of white scale. I filled it with water and added around 6 ounces of Muriatic acid to neutralize the scale and lime build up and let me tell you the rad boiled like crazy. I drained the rad again filled with water and ran the engine for a few minutes to get all the acid out. Next I removed one of the heater core hoses and used it to force water and flush the system out, a bit more lime flakes came out and the water that came out of the cooling system was as clean as the water going in. Now this is what I call a flush. I also replaced the upper Rad Hose and filled the Rad with the long life Preston Coolant and I hope all will be well until I decide to sell the car.