Replaced the waterpump, still overheating, need serous help.

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Firebrian
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Joined: Sat Sep 24, 2011 2:15 pm

Re: Replaced the waterpump, still overheating, need serous h

Post by Firebrian » Tue Jul 02, 2013 5:24 pm

I had a similar annoying overheating problem in my '68 Plymouth GTX 4 speed and eventually went through about every possible source in the engine bay to help correct it. After 3 years I never did find it even though I had changed out or adjusted about 15 different sources that can affect heat input or output from the cooling system. Even things like incorrect engine timing, spark voltage, air/fuel mix, engine upgrades (ie cams, compression ratio, etc.) can generate additional heat sources that your system wasn't designed for. You may still have flow restrictions somewhere in your system. A dirty radiator (inside chemical buildup or outside fouling) is a source that needs to be checked. Is the air dam still in place under the car? That directs air more cleanly up into the radiator. Those 1970 Superbirds were notorious for idling hot because they had such tiny entrances for radiator cooling air. Those air dams love to get caught on parking lot barriers and curbs. A dumb owner could have removed/damaged it and not given it a 2nd thought. The consdensor sitting in front of the radiator means if either one has debris on the outside your air flow is reduced. I've always used a piece of flexible screening material ($1) on the front of my radiators to keep stuff from getting stick in the fins. And it's easy to remove to shake clean. It doesn't reduce flow any either.

The radiator needs to have both proper contact time as well as mass-flow (ie M x V). Fwiw the only thing that really helped me (though only a little) was running my GTX on a weaker glycol mix during the hot months. I ran that as low as 10-20% coolant and 80-90% demin water. Water removes heat better than glycol. It has a slightly lower boiling point though. Water doesn't protect metal surfaces as well due the lack of anti-corrosion additives and detergents that the glycol has in it. I also added a bottle of Red-Line Water Wetter ($6-$9). With that setup the car ran about 5-10 deg cooler than it did on 50-50 glycol/water. It would still overheat on a hot day though if it was left idling for more than 5 minutes. The last thing I did to that car was to change the cam back to factory stock. Even that didn't change the coolant temperature. Everything from a record radiator, new carb, new cam, new plugs-wires-coil, optimal timing (initial + advance), higher octane gas (ie 98-102) and none of it ever "fixed" the problem. There were no coolant leaks into the engine either. My Mopar master mechanic and I could only scratch our heads in the end. If you do try less glycol ensure you get the missing corrosion/detergent additives back up to spec. Doing that on an iron 440 block could be different than an aluminum 350 block. Can't recall what combo of iron/aluminum blocks/heads the 1995's had. If the block already has fouled passages that won't show up except on infra red scans or abnormal coolant temps.

It's possible your car could have a couple of issues still lingering. If everything is already factory stock it makes your job a little easier removing potential causes. The radiator is the first thing to eliminate with a flow check or something. An 18 year old radiator could be gunked up. Was yours ever changed? Did an equal or better rated one go back in? The air locking already mentioned may still be an issue. But one would think that the air pockets would eventually move to the radiator and be expelled. A poorly running engine (its 18 yrs old and how many miles?) could also be an extra heat source. You could also borrow someone's Infra Red heat gun ($125 new) and shoot it at various spots around your engine and cooling system. It just might show up something. Check your suction side radiator hose during operation to ensure it's not trying to collapse and obstruct flow. It wouldn't take much. My GTX had a spiral metal coil in the suction house to prevent collapse. There also flow measuring devices that can be placed on pipes to determine internal flow rate. No reason why they wouldn't work on a coolant hose. Your mechanic might have access to something like that. The seller may have purposely sold you a bag of worms. Get more info on what they already troubleshooted. On any 12-18 year old car I'm going to assume that if there aren't cooling or ac system issues today from orig equipment.....there soon will be. A cracked overflow line might also imply cracks in your 18 yr old reservoir. But that worst that should do is not allow your radiator to stay full once it cools down. A poorly tuned/running engine, air pockets, or a clogged cooling passages (engine or radiator) are the more likely sources. You can troubleshoot your car for an extended period at idle with it running and radiator cap off. Did that more than a few times on my GTX.

Good luck.

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randybirdhawk
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Location: Haltom City, Texas
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Re: Replaced the waterpump, still overheating, need serous h

Post by randybirdhawk » Thu Jul 18, 2013 1:23 pm

I had overheating problems and checked everything until I realized I didn't check the back side of my radiator. The fresh air duct that sucks air from the bottom sucked a bag in and covered the back side of my radiator reducing the air flow across the radiator. After I removed it things were back to normal. I installed an SLP fan switch that helps a lot living in this Texas heat.
2001 Formula Firehawk #190
SLP 160°F Thermostat, SLP Fan Control Switch, SLP Skip Shift, SLP Tower Brace, SLP Air Box Lid, SLP Smooth Bellows, SLP High Capacity Radiator, and #241 Ported and Polished Heads
http://www.fquick.com/randybird

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