I can't get my '97 OBW to replicate the overheating problem for the dealer. So I dug into it myself just now, frustrated, figuring I'd swap the thermostat, get as much air bled out as I can, and go from there.

 

Funny thing is, though... I'm used to opening what I call the draincock... that faucet thing on the bottom right of the radiator (standing at the rear of the car looking forwards)... to drain the radiator, in addition to opening the cap and the bleeder cap. Opened that up, and got about 20 oz of coolant, all at a trickle. It was still trickling when I closed it up to post this, but it's definitely a trickle. If I open the radiator cap, I can see fluid just sitting there. If pop the cap back on, and blow into the bleeder hole, it spurts out, but returns back to it's trickle.

 

There was a bunch of gunk in the channel of the draincock... left over from oil in the coolant from the last engine, I'm thinking. Makes me wonder how much other gunk is in the radiator, and if that's what I'm looking at.

 

A clogged radiator?

If it's draining from the radiator peakcock, and the level in the radiator cap isn't going down, then yeah I'd say you have a plugged radiator.

 

Try taking off the lower radiator hose and see if the level goes down. If it does, I'd say try swapping out radiators.

I took the lower radiator hose off... and it went down alright. Most of it ended up in my makeshift bucket. I did get everything switched around alright, let it sit throughout the day, then bled it tonight. Tomorrow will be the first time I'll have driven it since the 'stat swap.

 

I've got a bit of coolant left over from the thermostat change... thinking about taking it to a local radiator shop and see if they can't pressure flush it, while sealing off every orfice but the draincock and wherever they're forcing coolant into the radiator. Or backwards. Or however they attempt to clean radiators internally.

Can you get a piece of hanger wire into the petcock to see if only it is clogged?

 

I've seen petcocks clog up because they are at the lowest point in the cooling system and frequently they are in a low flow area. Some sediments can gel or solidify up and a simple swabbing out will clean them. Also, is the petcock removable?

 

Jack

You could try a coolant flush additive. One of those that you mix with water and idling in the engine for 15 minutes. The flush two or three times.

 

I have seen this kind of stuff clear an old rusted and gunged up radiator. Make sure you use a weak solution (weaker than recommended on the bottle) and flush it thouroughly.

 

Brand names that come to mind: Lynns, Holts...

On my rad (96 Brighton), if you keep opening the petcock (unscrewing it) it removes competely from the rad. You might try that and see better what's happening.

I removed the petcock completely... still just a trickle. I might just try the wire trick, then the flush additive. Depending how much that all goes, I might try taking it to a radiator shop.

Be careful with the fush : dont neglect to read the small type on the can. I have one can (dont remember the name, it's in the car right now) that specifies not to let it more than 10 minutes in an aluminum rad. Dont know the kind of damage it could do, but I wont try to find out when I use it .

Good luck with the rad!