Cliff's Notes Version ;) (Long version follows)

The engine coolant in my 85 was boiling like the dickens a couple of times. I am wondering if there are any common causes of this that I should be looking out for?

Also my coolant temperature never gets above "Lo". What should I check first. I tried to get at the sender to try to unplug the connector, but it is really hard to get at. Any tips?

Normal Version

I have had my 85 for a month and two weeks (~3000 KM on it (~1864 miles)) and haven't had any problems with it so far. I kinda figured that my coolant temperature guage wasn't working right, but I wasn't sure. I had never seen it get out of the "Lo" range, but since I hadn't driven it on a hot day until yesterday I wasn't 100% sure of it.

Well, I was driving it to my parents place last night and when I was pulling into the yard my dad heard a gurgling sound. He came up and informed me of this as I was getting out of the car. I heard it as well and so I popped the hood. The coolant in the resevoir tank was boiling up a storm! Dad had me start the car up but it only made it worse, so we let it sit for about 20 minutes before it stopped boiling. He figured it might be the thermostat, so I headed to town and bought one. We installed it an hour or so later, then I took it out for a drive and everything seemed fine. It had been a reasonably warm day out, with it somewhere around 27 degrees C (80 F).

The only problem that we seemed to be having is that the coolant temperature guage never got out of "Lo", and the idiot light never came on. Methinks something isn't working quite right.

Anyhow, we headed off to the city early the next to get my air conditioning recharged and we didn't have a problem at all with the coolant. The resevoir never even got warm on the entire trip (120 miles) It was around 20 degrees C (68 F)when we got to the city. We dropped the car off and booted around the city for about 4 hours and went back to the dealer. They had just sent a guy to go pick up my car. Now itwas around 27 degrees C (80 F). When the guy returned he let the car idle for a couple of minutes, then backed it out of the way since someone was just taking a car out for a test drive. When we went outside there was a huge puddle of coolant on the ground and it was boiling again!

This time it didn't take near as long to settle down, probably only about 5 minutes. We refilled it and headed out since there wasn't much we would be able to do on a Friday afternoon 2 hours from home. We never had a problem the entire trip back. There wasn't too much stop and go traffic on the way out of the city, we were able to get on main roads with decent traffic flow.

So now I am wondering what could be causing this problem. I looked through the shop manual at the suggestions there.

Cracked head or blown head gasket? I don't seem to have this problem all the time, so I doubt it. I can't see any telltale signs of this anywhere either.

Bad water pump? Possibly, but again, I don't have the problem all the time.

Bad thermostat? Could be, but I did already change it once.

Plugged rad/hose? Possibly. It could be that something is partially plugged and it isn't letting enough coolant pass through the system to keep it cooled when the car isn't moving, but it is enough when I am travelling at highway speeds.

Not enough airflow through the rad? Could be. Some of the fins are quite smooshed on the air conditioner condenser, and this could be restricting the airflow enough.

The water pump is definately turning (whether or not it is working properly is unknown), and the cooling fan turns itself off and on. One thing I am wondering is if the cooling fan is running as much as it should be. Right now I don't have a working coolant temp guage, so I am not sure exactly what is going on. It makes it a real pain! I am going to try to get something working there ASAP.

What is the best way to go about testing the coolant temperature system? It is such a pain to get at the sender, and I can't seem to find anything regarding it in my shop manual. If you know where to find it in there I would appreciate it if you would let me know the page.

Anyhow, if you made it this far, thanks!

Any questions, concerns, comments?


[Modified by DF, 9:56 PM 6/14/2002]

 

You should have about a 50% antifreeze solution. Second, check the radiator cap seal or replace it. It would also be good to have the system pressure checked.

 

are your fans coming on????
you should clean the area between the radiator and the "air conditioner" radiator.....probably tons of debris in there that is restricting air flow
as for the temp sender... i forget where it is, i heard there were 2 one in the head and one in the radiator......but i don't think our years have 2....i believe it is in the head on the drivers side between 1&3...the aux fan switch is on passenger side between 6&8
CLEAN OUT THAT RADIATOR!!!!!!! that is where i would start! :cheers:

 

I will check the solution, I know that it is all out of whack now, but I will check it tomorrow anyhow. I can do a pressure test as well, but I think it is ok.

Yes, the cooling fan is coming on, but I don't know if it is coming on at the right temperature.

I haven't checked between the condenser and the rad, but I will try doing that. I would say that about 1/8th of the fins on the surface of the condenser are smooshed. Mainly right in the middle of the bottom in a semi-circle.

I know where the sensor is, but I can't figure out how the heck to access it. I can't get my hand down in there without removing a whole bunch of stuff.


[Modified by DF, 10:01 PM 6/14/2002]

 

don't forget to pressure test the cap also, if you see or hear the fans coming on when the engine gets hot , then i think you have a bad guage, my logic is , the sensor detects the water temp & comes on, the fan relays obviously works, otherwise the fans won't work, just my 2 cents, good luck, my sister lt4 CE reads a low coolant temp also, sensor and relays were checked, and all works :D

THE RADIATOR SOUNDS PLUGGED
:mad


[Modified by guywade, 7:34 AM 6/15/2002]

 

Well, I have the rad out right now. There was a ton of crap between the condensor and rad. I ended up taking the garden hose to the rad since it was so plugged full of stuff. I could hardly see light through it, so I imagine that this was the problem. :crazy: Now I just have to go and straighten the fins that are bent. What a job that will be :rolleyes:

 

Well, I have the rad back in and everything seems fine. I had a nice uneventfull drive back home from my parents place. :)

Took quite a while to get the crap out of it and to straighten the fins, but it seems to have been worth it :)

 

If you get "Lo" in a temp reading, the sensor is bad or disconnected.

 

Don't forget to check the following:

-Check the radiator cap and replace if necessary.
-burp the system.
-Make sure the coolant overflow tank has coolant in it.

 

If you're fluid boils, it usually means there is not enough pressure to raise the boiling point of the coolant. The other possibility is the presence of air in the system. If you're gauge is reading inaccurately, it is either a faulty gauge or air in the system.

So what you need to do is:
1. Check fluid level in radiator AND reservoir
2. Burp the system
3. Check the radiator cap
4. Check the thermostat and make sure it isn't sticking

Good luck!

 

It is all done guys ;)

I pressure tested it and everything, I think that the only problem was that the rad was plugged up with debris.

Now to deal with the sensor :rolleyes: