Can you help clear things up for me? Coolant temp problems.

geraba · 02-17-2011, 06:45 PM

Hello I have an 84 944 n/a and I haven't had it that long. It seems to me that this thing wants to overheat when I come to a stop and going down the highway when its 75 degrees out it runs on the 3/4 mark. I changed the thermostat and also changed the radiator cap and flushed the system and bled off the air but it didn't help the situation. We opened up the bleeder with the engine running to see if the water pump was pumping good and it did not spray out, the coolant just sits there and we also pulled off the heater tube and it also did not spray out. It leads me to believe that water pump is not pumping but I don't see how that can be the case when I can drive it 30 miles and it has never boiled over or anything like that. Am I thinking wrong or what do you guys think? I'm completely lost. I don't know if maybe i have to much faith in the guage and there really isn't a problem. I'm just confused why it wouldn't not spray out of the bleeder or heater tube. Thanks for your help

John_AZ · 02-17-2011, 08:16 PM

geraba,

Are you certain you have all the air pockets out of the cooling system? Do you know how to really bleed the air out?

Then, are you radiator fans coming on when the temp gets to half?

Do they stay on? They should stay on until the temp drops to about a third +-
If the fans do not come on or the fans go off early...get a new radiator fan relay/switch.

You could get the OEM temp---marked on the fan switch or go to a cooler temp. I am using a 75degree C. But it is hot here in AZ. There are roughly 3 temp ranges. 75/82/92C. ~82C is normal.

The other thing that seldom happens---------but it does------the waterpump impeller slips off the shaft.

GL & welcome,
John

HondaDustR · 02-18-2011, 12:17 AM

The cooling fans don't kick on for mine until the 3rd line. Once they do, the temp drops. Maybe the radiator is partially clogged. or the fins are blocked. I have a feeling mine needs some cleanup. The temps usually dropped right down when the fans kicked on, but last summer, I had to rev the motor a little to get the temp to come down. You could check the ground point up behind the dash behind the fuse block to make sure the dash is getting a good ground.

Aenyone · Aenyone's Garage

I had trouble with mine, similar to your problem. I couldn't sit in a long line (like a drive through or a really busy intersection) before my temp would get too hot. Turned out to be a clogged radiator with a pinhole. I think the metal clamps on the plastic tend to break the radiator after 20 years.... put in a replacement and it has been fine ever since.

geraba · 02-18-2011, 07:38 AM

Thanks for the reply guys I hope that I'm getting the air out right doing the whole mouth to mouth on the coolant tank. The hardest thing I don't understand is I can take the blessed completely out with the car running and the coolant doesn't spray. I can squeeze the hose and get it to squirt out but I have a hard time believing this thing can not overheat with no water flow. Am I thinking to American for this car maybe?

HondaDustR · 08:59 AM

I've found that the bleeder screw does not like to flow much even when the engine is running. I've had the most success bleeding by having the expansion tank dismounted so I can elevate it while cracking open the bleeder to force some positive flow. That is also my prefered way to fill it before running as well. It's a PITA system until you figure out the tricks. The newer american stuff has gotten alot smarter. One truck platform I've dealt with ran an expansion tank, but the way it was piped, there was always a small flow through it, which did very well to auto bleed the air out.

AA_Ezra · 02-18-2011, 09:11 AM

dont forget to put the heater on the "HOT" position. my little trick what i do if you have the time is to jack up the car on the coolant Res side of the car to help gravity feed all the spots. Then every so often i squeese the top Radiator hose to get rid of air bubbles. after a few min the coolant res tank settles and no more coolant is needed. Set the car down. squeese the top radiator hose again. Then i jack up the front of my car ( mine is lowered) so that the bleed screw kinda becomes a high point. i then open up the bleed screw and squeeze the radiator hos untill coolant flows out. and close it before i release the squeeze pressure on the hose. and keep repeating untill there's no more air.

That's basically how i do it, it's time consuming but if it's done right i wont have to do it again for another 2-5 years when the coolant needs to be flushed?

Don't forget to use distilled watter.. wall-mart gots it pretty cheap

Or you can just open up the bleeder and put a water hose on the coolant res untill only watter flows out of the bleeder screw :P

It wouldn't be a bad idea to use the water hose idea to just flush the radiator. alot of calcium and lime buildup came out of mine, even more when using one of those 5 min prestone flushes

krystar · 02-18-2011, 10:24 AM

if no steam/water is spewing out of the bleeder hole when the engine is HOT, then there's an issue.

when engine is hot, does the upper rad hose feel hot? is it under pressure?

geraba · 02-18-2011, 12:16 PM

Yes the hoses get hot and so does everything else and as far as I can tell everything heats up equally including the heater core. The heater works pretty good. If you take the radiator cap off when hot and running there is only very little pressure. Also another possible clue it seem when you turn the heater on it makes it worse. I figured it would help cool things down

Slam · 02-18-2011, 12:29 PM

Big clue: turning the heater on makes it worse. You've got air trapped in the system for sure. Try a bleed every couple of days over the course of a week. As stated above, it takes a while to learn all the tricks, and even mouth-to-mouth won't get all the air out.

The biggest single thing you can do to improve matters is change the rad.

panama944 · 02-18-2011, 09:11 PM

I have not had the luck to change my thermostat yet, but have read Many times in MANY different places to use an O.E. thermostat! The cheapie parts store stuff "including Nappa, are multi make units that fit many apps. Some better than others. I have heard of these trapping air and making bleeding impossible! Start by trying to get all the air out, then if you still have a problem and diddnt use an O.E. stat, get one. The radator is a possibility, but expensive.Try the low $ stuff first. As a side note, keep the ratings of the thermostat and fan switch in the same catagory. You should not use a low temp stat with a med temp switch for ex. There is a balance between the two. Good Luck!!!

mattdavis11 · 11:12 PM

I've always jacked up the front as high as I can, opened the bleed screw and filled through the reservoir. It takes some time, but when you get a stream of liquid out of the bleed screw, you're good. Follow that up with periodic checks, ie. the next day, a month later, and next year.

It's possible that your radiator tank has cracked on the driver's side, top portion, and the water level is just a bit below the thermo fan switch. The fans don't work well then, there's no water to sense.

Outside of that, start the car, then whack the top of the dash while watching the cluster.