Just patched the plastic part of the radiator on my '99 Blazer. Read somewhere that I could replace the existing radiator cap (15 psi) with a lower rated cap (say 8-9#'s) so that there would be less pressure on my patch. Do you think this is a good idea?

 

Not really, These systems are designed to run these higher pressures. You could run into a lower pressure cap affecting temps etc. Repairing these plastic radiators doesn't work. Replace it new ones are only around $125. I'm an old mechanic & have tried once to repair one of these plastic radiators & it held about a day or so.

 

I appreciate your advice and that's exactly what I'm going to do. Replace it. Didn't know they were that inexpensive.
Just patched it y-day with Quicksteel. (Crack was in a very accessible place and I didn't even have to remove radiator!) Anyhow, it's seeping already so enough of that. It was worth a try, I guess.

 

The high pressure is what allows the coolant to run at temps higher than the boiling point without boiling over a low pressured rad will boil the coolant.

 

Thanks XM...., I didn't know that. Hmmm. I put in the new radiator today and now would like to know the proper way to refill it with fluid. I was just putting water in it for the last week or so since it was leaking. The radiator had a sticker on it that states that I should flush it (otherwise the warranty will be voided!) I don't think I need to do that since I've ran a few gallons through it recently. The water jacket has very diluted antifreeze in it right now and my plan is to put in straight antifreeze until it's full and then check it to see if it's in the 50-70% range. What d'yall think about this plan?

 

I would flush the complete system heater core and all, use a flush product and let water run through the block until it coming out crystal clear then drain block and refill with your antifreeze mix. Depending on your location and how cold it gets you can run as little as 20% coolant/80% water. Thats what the mix in my jimmy /5.7 is because it runs hot and Water cools better than coolant does but you need the coolant to raise the boiling temp. In your case on a stock truck 50/50 would be fine but don't buy premixed it's more expensive. I would also use prestone antifreeze and not the dexcool.

 

Well, I flushed it out. Ran water through the tee til it came out clear. Then (because the drain valve is so inaccessible!) I opened the one hose (lower one) to drain out some water to make room for antifreeze. Opened the tee and that released more. Then I put in about a gal. of undiluted AF and maybe a half gal. of 50%. So I should be good. I'll take it to the local Advance to get it tested as I don't have one of those.
Now since that problem is solved, I gotta replace the tensioner pulley (again!) It is squealing badly. I spray a lil' spraylube into it and it shuts up for a min. That irritates me since I replaced it less than two yrs. ago. Are Blzers known for this? I would like to get a better grade of pulley so that this doesn't happen again so soon.

 

is your belt too tight? if you look on the body of the tensioner there is an arrow trying to point between 2 lines, and should fall between them......just something to check....

 

I dunno. I will look there when I replace pulley tomorrow evening. Is there a way to back off the tension? It feels very tight when I release it to do whatever but I thought that's just the way it is.

 

If the squealing is the bearing in the idler or tensioner pulley this can happen on any vehicle. I have found new bearings with almost no grease in them, and they will not last long that way. I always carefully remove the seal from new bearings of any type and add grease if needed. You can also add grease this as preventative maintence. I have never had to replace a bearing that has been kept greased.

If the bearing feels rough at all don't bother with the grease as the grease will let it last a little longer but the beraing will eventually fail. It is ok to add grease as a temporary fix until you can get a new bearing. On metal pulleys you usually can just replace the bearing instead of buying the complete pulley with bearing and save some $$.