89 Accord Radiator Confusion – Help?

The Background

I have a 1989 Honda Accord LXi, 2.0L L4 SOHC 16V, Manual Trans, 4-dr Sedan, Non-CARB (49 state), Fuel Injection, 248K mi.

I recently replaced the water pump (w/p) myself. Yep this is one of the external water pumps over by the alternator, not tied into the timing belt. Probably did not do things in the right order as when I pulled the w/p I did let a bunch of fluid loose. Also, I did not remove the timing belt cover, just removed the cover bolts on the side that effected the w/p. Yeah, it was some “fun” getting the w/p out from under the cover and wedging the new one back underneath, but I managed.

So when I got done buttoning everything up, refilling and bleeding air out of the system, I restarted the car. To my utter horror, I saw a steady, pencil-lead thick, stream of green fluid coming out from under the timing belt cover. Ugh!

So I shut things down, put my tail between my legs and drove down to the car guy that specializes in Hondas. He was too busy to take a look at it but scheduled me in 3 days later. I drove home. Had ZERO problems during the drive there and back: i.e. no high temps, no raised temp levels and no over heating. I watched the temp gauge more than the speedometer and I drove the local streets and not the freeway.

By the time I got back to the shop 3 days later there was no sign of a drip or a leak. The tech ran a pressure test on the system and reported a “small” leak in the radiator at the connection between the core and the tank. He didn’t say exactly where (top/bottom). He wanted $400 to slap a new radiator in. I declined figuring this is an easier fix than the w/p. As it turns out low end parts for everything are probably under $100. Subsequently I have seen no drips on the garage floor.

Questions & Discussion

So now the confusion and questions, if anyone would be so kind.

1. Leak or Residual? I am assuming that through the removal and installation I let a fair amount of fluid loose and that built up inside the timing belt cover? Once the engine started, the forces interior pushed the fluid out. If I had let it run 15-mintues it might have stopped dripping and been done? Does this make sense?

Alternatively I read a thread somewhere where the author mentioned “burn in” of the w/p seals before they were 100% sealed. Mentioned that to the mechanic and he didn’t salute the idea. Do new OEM w/p’s really need a break-in period to be sealed?

2. Which kind of radiator do I buy? When I put the VIN into the eStore Honda site I get TWO different brands of radiator: Toyo and Denso.

Plastic vs Aluminum
Now I have done some looking around and I “think” one of those is a copper core radiator and the other is an Aluminum core. So that is one thing. I have done a bit of looking around on the ‘net about the debate of copper (Cu) core vs aluminum (Al) core. From what I can tell is that Cu is the most efficient at heat transfer, while Al is the lightest. So for engines that run hot Cu might be better, where as if weight is an issue use the Al. I’m not sure if heat is an issue with this engine and I’m not racing so not sure if a few extra pounds would be an issue? So, if I can do it reasonably (i.e. one of the OEM parts I have found) is a Cu core, I’d probably do that.

Plastic Tank Vs Metal Tank
Now all of that said, the tank still is plastic! Ugh. The car had the original radiator crack when the car bottomed out on a bump years ago. So, this is a replacement radiator and who knows if the original was Cu or Al? Since this appears to be a component that is vulnerable, I’d rather get a metal tank that could be repaired. In looking around I think I can find a metal tank radiator made here in the USA! Is this crazy thinking? Overkill?

Plastic Tank Repair?
Then, in looking around body repairs, I stumbled on to Plastic Welding and plastic welders. Hmmm, why not just go to the auto parts store, borrow/rent their pressure tester, find the small leak and apply some plastic welding techniques?

3. Coolant & Coolant Additives. The auto parts store said with my older car I needed “old style” fluid and not one of the new-fangled mixes. They sold me something that was supposedly straight ethylene glycol. I mixed that 50-50 with DISTILLED water. [checked with a hydrometer for protection to -20F] In the process I bought a bottle of Royal Purple additive and was going to add that. However, further reading in either the Service Manual or Haynes suggested that additives might be a bad plan. I returned the Royal Purple. So, I am wondering if the additive would help? I know way back, when the dealer did oil changes they always added some Wynns, so I am wondering if additive in the cooling system isn’t a good idea as well?

So yeah, too much time on my hands and probably over thinking too! I’m interested in what other know or can suggest. Thanks!