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Getting hot


Guest Telco

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Guest Telco

89 Reatta

Now that it's getting warmer, I've developed a new problem. Last winter it was not warming up at all, easy but miserable fix with a new thermostat and hoses on a 10 degree day. But now, when it's about 78 or below outside everything is fine but when the temp goes over 80, I start having cooling issues. The fan motors didn't feel like they were pulling much air and were looking pretty ragged so I replaced both of them, and it helped some but not enough.

When I idle on a hot day it will warm up, the fans come on and it cools, then it starts warming back up. It's hit 210 doing this. When I'm going 40-45MPH it goes back to normal, but then gets worse when engine RPMs start going up with speed. When it's cooler the thermostat operates correctly, goes from cold to 199, then drops back down to 180, then averages out to about 192.

Rad fluid is good, was changed when the thermostat was changed. Upper and lower rad hoses were also changed at the same time, so these parts are good.

I'm seeing this as a possible bad rad cap, bad radiator or bad water pump. No antifreeze leakage, but then a weak pump doesn't necessarily have to have a bad seal. I'm leaning towards a bad radiator. Just want to make sure I don't miss any other possibilities before slapping a new rad in. Thanks.

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The problem with the 1988-1989 Reattas (and Rivieras) is the ability to read the exact temperature. I think you should turn on the radio and forget it.... there is no indication in your message that the car is getting HOT (overheating),

Denny Manner, a Buick powertrain engineer claims they ran 3800 engines for long periods of time at 230 without problems. The ECM does not turn on the pusher fan until somewhere around 220.

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Guest Telco

Man I don't like that at all.

The gauge does work right, the temp gauge reads exactly as it should when the thermostat opens, and the numbers show exactly what they should for the thermostat's temperature reading.

I may go ahead and put another radiator in though. If it's running this hot when it's 80 I don't want to see what it does at 105.

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Putting in a new radiator probably won't help. Even a new radiator is not going to cool the water while you are sitting in traffic unless the fans come on to blow air through it. The problem is with the fans waiting until the temp reaches about 230 before they come on. Having the PROM reprogrammed is the answer to the engine running cooler when stopped in traffic and not moving.

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Guest ekvh

Everybody's does it unless you do what Padgett does. Do a search and everyone here freaks out at first, but they have a good reputation as a reliable motor. If you have a LeBra on the front end, it will heat more and cool less due to the openings in the LeBra not being large enough. I am hoping to get some trim and enlarge mine soon. The 180 thermostat without the PROM adjust to turn on fans earlier only helps in the first 30 minutes of driving or so. Others here have wired their outer fan to kick on along with the inner one. The problem is the PROm doesn't turn the fan on until 210 and it doesn't begin cooling for a few minutes after that. Take Barney's advice.

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Spent a lot of time in the Delco experimental garage and "hot soaks" to 230-250 was common and did not affect reliability.

Of course we were only concerned about 5/50. All of my cars are past that.

What I have found over the course of several decades is that *everything* lasts longer when you keep the engine 10% cooler: belts, hoses (liquiid and vacuum), wiring, connectors, etc., etc. Also I have found that a 180 provides lots of heat even at 0F (limit of my experience with 3800s). Finally, once you pass 160F, the computer is "all in" and running at its most efficient mode. 180 is fine.

I took the LeBra off because the coolant was running about 10F hotter below 50 mph. Beyond that I have lived mainly in hot climates and an engine is happier at 90/90 than at 100/0 even if people aren't. Florida is good for cars.

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Guest Telco

I could understand that at a stop, but it also runs hotter over 50MPH. Not going to worry about it for now though, can't get the driver's door open and it's something I did to it, unfortunately I don't know what I did. New thread on that.

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"hotter over 50MPH"?....strange.

If I'm on the highway.......going 50mph or faster.......with all that airflow.......even if outside temp is in the upper 90's......my coolant temp is pretty much pegged at the common 192F. I find the most stable temps to happen when at constant speeds in the 50+ range.

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Sounds like the radiator tubes are getting clogged. Have you had the cooling system flushed/flow checked ? Other possibilities: collapsing hoses, corroded vanes on water pump. Good radiator shop should be able to diagnose.

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Guest Richard D

I have a friend who has a 66 Mustang coupe and it would run normal at idle even with the A/C on. But when driven it would show hot on the gauge and overflow water. Radiator was five years old with about 1,000 miles on it. New water pump, no change, new hoses ( thought lower hose may be collapsing) no change. New radiator problem fixed. When the old rad was cut open bottom half was full of crud, bits of aluminum. Where it came from no one knows.

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Guest Telco

I'm thinking radiator too, because of the heating up over 50MPH. The engine will make more heat when the RPMS are up, and if the surface area isn't there it won't cool. I'll get to it in the next few weeks.

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Guest Richard D

I just called Bob and asked him about the crud in the barely used radiator. Turns out it was from the manfacture, as bits of weld flash and aluminum broke off and collected in the bottom of the radiator, since it sat for a month at a time it turned solid. It was an aluminum rad painted black to look original.

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Guest Leroy Cook

My 91 gets hot when I am in town and the AC is on. I am thinking about getting a larger electric fan with a sensor to turn on @ 200 degrees. My fans are not turning very fast and I don't know how to program computor.

230 is just to hot for my taste!

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My 91 gets hot when I am in town and the AC is on. I am thinking about getting a larger electric fan with a sensor to turn on @ 200 degrees. My fans are not turning very fast and I don't know how to program computor.

230 is just to hot for my taste!

I used a sensor to turn on the fans in my '88 model. Like you, I couldn't program the computer and I was not successful in getting someone to do it. Below is a link that tells how I did it.

Coolant Fan Control Relay Modification*-*ReattaOwner.com

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88 is different in the LO speed on 89-91 the LO speed has both fans wired in series so both turn at about half speed. The 88 has a resistor block on the puller fan and only it turns at LO.

89-91 is the better method but requires a relay block (one more relay) and wiring harness from the later model to install on an 88. I just jumpered out the resistor so I have one fan at full speed at LO and both at HI. My computer is also reprogrammed to bring the LO fan in at 185F and the HI at 189F.

Unfortunately lately I have had trouble with being unable to reliably burn old PROMs and while I have new PROMs and carriers, I have no time to replace them since are soldered in.

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