SI Replacement Radiator Opinions

[CaffeineRacer]

Just curious if anyone has any first hand experience with the replacement radiators SI sells?

They state that these are only 2 core (as opposed to the original 3 core), but "exceed" the OEM cool efficiency. I assume they use denser fins to achieve this.

At any rate, just want to know if anyone can attest that these units in fact do cool at least as well as the original 3 core units.

I am also looking into getting my current one recored and reconditioned. I'm not interested in an aftermarket aluminum unit.

Many Thanks.

[Gunslinger]

I don't know the cost of the SI replacement radiators, but try getting a quote from a radiator shop for recording yours with a unit with increased fins per inch. It may be a more cost effective way to go.

I'd ask some local car clubs where for recommendations of a good radiator shop.

[CaffeineRacer]

The SI replacement is a staggering 650 +shipping. I'm taking it to a shop later this week to get an estimate and see if they can put in a core with slight tighter fins for increased cooling efficiency.

It is my understanding that the fin density (up to a point that does inhibit airflow) has a greater impact on cooling than the number of rows.

[Gunslinger]

From what I've read added fins is more efficient than adding rows. That's due to all the fins being directly exposed to the cooling air. Added rows get air heated by passing through the previous rows. It's something like losing 50% of the cooling efficiency each succeeding row.

[Cowboy91]

I took the radiator from the '70 to the local shop and had it tested for leaks and flow. During the discussion of rebuilding of the factory one with a new core and changing the top outlet so cut out the inline fill/pressure cap was about $350. Three years ago I had one done for $150. Difference, the copper of the core. If you go to aluminum, be sure to ground strap the radiator to prevent electrolysis. Seen several that after two years of use are leaking due to corrosion.

[Billy Shears]

I'd be interested in this. I may need to replace the radiator in my Avanti. I'm going to keep driving it for a while and keep an eye on things, but it seems like my car is running just a wee bit hot, even after the Saturn air dam was installed.

[CaffeineRacer]

So I dropped the radiator off at the shop today and described where I found leaks and the guy thought that if that was all it would be less than 100 to clean up an fix. He also noted that some of the solder joints looked slightly oxidized from the outside. He did also mention that if it did end up needing to a new core it would be about 550 all in.

I also discovered upon removing the radiator a ton of hair and crap stuck in the upper half of the unit. Not sure where it all came from, but I'm sure cleaning that off will help with cooling.

I'll keep you updated once I hear back from the shop.

[Gunslinger]

Billy...

Just because it's running a bit hot doesn't necessarily mean the radiator is the problem...it could be...but don't start throwing money around without doing a complete diagnosis. It could be engine timing needing set properly, a bad radiator cap, the lower radiator hose going bad, the engine block with a restriction in the cooling passages, a bad sending unit or a bad gauge, a loose belt...plus other things that could individually or in concert with another problem.

[Billy Shears]

Billy...

Just because it's running a bit hot doesn't necessarily mean the radiator is the problem...it could be...but don't start throwing money around without doing a complete diagnosis. It could be engine timing needing set properly, a bad radiator cap, the lower radiator hose going bad, the engine block with a restriction in the cooling passages, a bad sending unit or a bad gauge, a loose belt...plus other things that could individually or in concert with another problem.

Oh I have no intention of doing so. But the car was running even hotter than this before, and a valve adjustment cured that problem. The cooling system was flushed at the time as well, and pressure tested. I'm trying to avoid replacing the radiator actually, but if it becomes necessary, obviously I want the most efficient one I can get.

[CaffeineRacer]

Quick update. Radiator shop determine that it was a leak around one of the fittings for the transmission cooler lines (lower one). I was not at all surprised because I've been struggling with those cooler lines leaking and have been torquing on them quite a bit lately. He gave the radiator an overall "C" rating because of oxidation around the solders that connect the tanks to the core tubes. So my options were to repair the leak, clean it up as best it could be outside and inside and call it a day for $80 knowing that it would no longer leak and cool slightly better, but will nonetheless eventually fail but probably not for a few more years. Or get it recored for $500 and it will be good for a long time and probably cool better than ever before.

I opted to repair the leak and clean it up. I picked it up today and I've got it install. No more leak!! They cleaned it up very nicely. Straightened some bent fins, soldered a couple of weak spots and repainted it. For $80 I think that's an absolute steal.

I've ran the car up to temp in garage and so far so good. I'm going to let it cool down over night, recheck my hose clamps and coolant levels, then take it for a test drive.

On a note to the original thread topic I will say that in discussing getting it recored he mentioned that the new core would cool much more efficiently and be more durable than the original. It would still be a three row core, but with much tighter packed fins and the materials they use now, while still copper/brass are much stronger. My guess would be that the $500 recore would be more efficient than the one from SI (as it is only a 2 row) and much cheaper.

[dstuff5]

I'm reaching here a bit my 73 radiator leaks and before I take it to radiator shop, I have a radiator form a "67 Pontiac GTO 400 with Turbo 400, could this be fitted?? As I said I'm reaching. Thanks, Dave

[warren55]

As for the Pontiac GTO radiator, I'd be surprised if that is going to work but I'd think it would be worth a bunch to a guy who has a 67 GTO with a 400!

As for my 73, the radiator cooled just fine when I got it but it had an annoying leak between the core and the lower tank. Some advised me to just put some stop leak in it and live with it since I rarely drive it.

Since I'm not one to leave not quite right alone, I took it out and took it to a local, well respected radiator shop. He condemned my core and my transmission cooler, saying it had just been around for too long and had lived a good life. He said he could patch it up for about $100, but it really needed to be recored and it would be better than new for $500. I of course opted for the $500 better than new option. I got it back and after replacing the water pump, thermostat,hoses and belts along with my newly reincarnated radiator, I replaced the hood and prepared myself for what would certainly be the most bullet proof cooling system in my region. (Did I mention the new fan clutch and fan?)

After living in denial for a few months, I realized that my radiator still leaked in almost exactly the same spot. The radiator guy said no problem, bring it to me and I'll check it out. After a week, he delivered it back to me with apologies. He said it had a leak between the core and the lower tank, but as soon as he heated it up to remove the lower bracket it stopped leaking. He assumed that some solder had flowed to where the leak was and stopped the leak. Nevertheless, he removed the bracket and cleaned everything up again. He then reattached the bracket and pressure tested it again, "daring it to leak!", but it was all good now. He said he guaranteed it would not leak, unless it did.

It did. I refused to take it out again. I should have put in the GM stop leak in the first place, because that's what I ended up doing. It still runs at 180 to 190 after throwing about $700 at it and more than a few hours of my time.

Rant over....

[Avanti83]

I'm reaching here a bit my 73 radiator leaks and before I take it to radiator shop, I have a radiator form a "67 Pontiac GTO 400 with Turbo 400, could this be fitted?? As I said I'm reaching. Thanks, Dave

If you own a welder, metal brake, a gallon of fiberglass resin and cloth then anything will fit. Realistically, it's hard to make the radiator opening a different size so I'd do what Warren suggests and sell the radiator to GTO guy.

Stopleak works usually but the problem you are trying to solve is a weak radiator and they usually don't get better with age. You'll just keep following the problem around and then the whole thing will dump the radiator contents on a remote highway just outside of cell phone service ruining the head gasket and possibly worse.

Unless you have an aversion to aluminum, you can replace yours for under $250 and never need to worry about it again.

and it's a lot easier than adapting something that doesn't fit.

Speedway sells a radiator of the correct size for $129 and your local shop can TIG the correct brackets on for probably $100. You'll need to find a different lower hose but we can help with that.

BTW,. Welcome, Bob

Edited July 14, 2015 by Avanti83