fresh rebuild overheats.

1986 GXL

Emssions removed
Fresh rebuild
FPD removed

Outside Airtemp was in the mid 80's (farenheit)

I ran the car for an hour while adjusting the idle. The water temp was slightly over halfway up the temp guage.

I shut it off for an hour.

I Ran it again for an hour, at roughly the same place on the temp guage. Drove it less than a mile with temp creeping up to about three quarters up the temp band. I then parked it and reset the timing with a timing light. While parked, the temp climbed near the end of the band so I shut the car off.

I was keeping track of the temp of the upper hose and lower hose with a remote (laser) themo. I noted the top hose was hovering around 160 and the lower around 140. Does a twenty degree spread seem acceptable for pre-radiator and post radiator?

The overflow container started to boil and continued to do so for a few minuets while i put my hands over my head and taught my dogs every explative in the english language.

I rebuilt my car because of this problem.

I have the stock fan and radiator in the car. The fan spins about two blades past center while warm if it is hand spun (about one eighth of a rotation) so I assume that is still good. I have the Fan shroud on (as well as the under engine shroud), the radiator still allows a garden hose to pass pressure through and has good baffles (fins) with few bends. Water pump is after market but still funtional with no weep from the hole, Thermostat is OEM and brand new with a gasket, i'm running 50/50 coolant, full oil.

I ordered a new Radiator and am going to install a flex fan.

Has anyone experimented with advancing the timing? Does that yield cooler temps?

Any other ideas?

Thanks Guys. I'm stumped.

 

have you tried an aftermarket gauge?

 

^ if the coolant is starting to boil it doesn't sound like just a gauge issue.

Back to the OP: Did you get the air out of the system?

with the engine completely cold the clutch fan should have significant resistance when you turn it by hand. Why did you order a radiator and electric fan (which has its own set of challenges) when you haven't even bled the air out of the system? Why didn't you take the radiator to a radiator shop to be tested? With an electric fan conversion you now have to worry about a control system for it and there's no guarantee it will fix your problem.

Were all the coolant passageways ok when you rebuilt the motor (no chips etc near the o-ring groove)? Which coolant seals did you use? Did you install them correctly per FSM instructions?

 

I followed the FSM for filling the coolant. Cold car, bleed screw out, fill till weeping. tighten, fill remainder of neck. I also did this with the car running.

also the engine was rebuilt by rotary resurrection.

 

ahh...i missed that part

 

My fan has resistance, but as I say it spins a bit, about 1/8th of a turn. Preferably i'd like to install a flex-type fan, not an electric fan. Is anyone using that sort of fan on their car?

 

Thats super weird, I wouldn't mess with timing as that would be a bandaid. There is something seriously wrong, whats the story with the thermostat? Where was it purchased and what brand? Did the car run good before with that t-stat? I ask because some aftermarket t stats are supposed to be junk and that seems to be the only reasonable culprit considering that you aren't even driving the car hard.

 

I would have to agree about changing the thermostat, that is an inexpensive place to start. The car should not overheat while idling, doesn't matter if it is a stock radiator. The stock clutch fan is great as long as the clutch is functioning properly.

It is possible that something was missed in the rebuild inspection. A warped plate, cracked coolant seal retaining wall or pitting around the spark plug area inside the rotor housing (this can be hard to inspect)

 

well rebuilds are tough to bleed the air out. remember the entire engine was apart so it will take time to get all the air out of the coolant passages and hoses.

 

OP already mentioned the T'stat is OEM and brand new. But hell, if all else fails try another? Maybe he got super unlucky and got a bad one?

Is the low coolant light on? That light is reliable and there for a reason.

On my recent rebuild I had my light come on, but go off periodically. I ignored it because it would go away, and my car ran in what I thought were acceptable levels around 210, idled at 195. STUPIDLY I ignored it and nearly killed my engine. I guess we all get one overheat because I nearly hit 240 and thank the maker, I didn't lose a coolant seal.

It turned out my upper return heater core hose had a slight leak. Not visible when idling. I tightened that clamp to as much as I could, and checked all others.

Now I bled the system again and my car will not even get to 195 driving around even when it's hot as ***** outside, and it idles at 180.

Check all hoses and connections. Next, fill up and make sure you are topped off on coolant. With everything back in place, gently squeeze the upper radiator hose and listen for noise. If you hear any hissing, like air escaping, a connection is bad. If you hear gurgling, it could be air bubbles.

 

I would be inclined to agree with most of the posts on here and say make absolutely sure there is no air in your cooland system. this exact same thing was happening to me with my new rebuild from rotary resurrection strangely enough.

The best way to make sure there is no air in your system is to put the heater on full blast in the car, then open the upper coolant filler cap. then start the car and pour in coolant until it is about to overflow. then put the cap back on.

 

The best way I have found to get air out the system on a new rebuild is with a Lisle funnel. It has an adapter that seals the water neck and has about a two quart capacity. I could only find the Lisle funnel on line. But I checked with NAPA and they sell it under the Balkamp brand. NAP had to special order it , but I ordered it in the morning over the phone and it was at the store by 1pm.

I like to put the funnel in place, then fill the system up, using the bleed screw or radiator cap til full. Then continue filling until the funnel is nearly full, start the engine, put heater to full hot and wait until the TStat opens. You should get some large bubbles in the funnel. You may want to sqeeze the upper radiator hose to help the fill pocess. Then refill the funnel and let the engine cool down with the funnel in place. I use any excess coolant in the funnel to fill the over flow tank.

Always worked for me.

 

The Lisle funnel is what we use as well to burp every engine that we install. Great tool to have, far less messy then filling the cap until it overflows. Makes it much easier to check for leaks while the car is running and allows all the air to work it's way out. It also makes it much easier to do the "bubble test" to see if exhaust gas is getting into your coolant system.

 

It is a great idea to let the system cool down with the funnel. I also lifted the front of my vehicle to get the air out.

 

I work as a ford/mazda mechanic and I gotta say this thing is GOLD! makes coolant jobs 10x easier.