78 brat... still overheating. advice?

[ninefourteener]

So she's on the road legally now . I have been driving her for the past couple days and she is doing well . last night I took her on the highway for the first time . still overheating venting steam out the radiator cap .

 

i have changed the thermostat . i have added the dual fan system . everything seems to beat working perfectly . Except still venting steam out of the radiator cap .

 

it seems to be a bit worst when i turn on the heater .

 

Suggestions?

 

-- Submitted via my HTC EVO 4G

Edited September 4, 2010 by ninefourteener

[EvilDead]

Get a OEM radiator cap? What's the actual temp on the gauge when ya see the steam?

[Allouez]

Hope it's not a head-gasket ... That can make a car run hot. Happened to me some years ago. Does it run rough when you first start it? Also, if you can smell antifreeze and it blows a little white 'smoke' from the tailpipe, those are indications of a bad head-gasket.

[ninefourteener]

No... she starts right up... runs great... no white smoke... no antifreeze smell. Pretty "fuellie" because I think she's running a bit rich, and there is no cat on the car.... but there's no white smoke or watery/antifreeze smell.

 

I've been driving her for 4 days now..... and she's done great. (short 20 minute drives)

 

Until last night.... I took her on the highway.... got back to a slow speed, and I figured I'd test out the heat..... and it blows cold...... and I noticed the temp gauge went up when I turned on the heat..... and then down again when I turned off the heat.

 

But still the heat isn't blowing warm at all.

 

The steam is coming out of the little nipple right on the radiator by the cap.... not actually out of the cap itself.

 

Suggestions????? I really don't think it is a head gasket. Oil is clean too (no water in it)

 

EDIT: And right after I wrote this.... I went to check how low my radiator is... and it was almost empty. Almost every bit of the water had vented out that little nipple by the radiator cap.

 

EDIT#2: I'm starting to question whether or not I installed the thermostat backwards. Would that cause it? I honestly don't remember which way I installed it.... only that I put it in the same way the old one was (which could have been done incorrectly). What would be the RIGHT way to do it?? Pointing to the radiator, or the engine?

 

Also..... I'm questioning whether or not the water pump is bad. What is the easiest way to tell???

Edited September 4, 2010 by ninefourteener

[ninefourteener]

So.... I let it run in my driveway..... for a LONG time.

 

Barely went above the first mark on the temp gauge.... perfect.... not overheating..... nothing.

 

... and the heat is blowing warm... just like it should.... because (obviously) it has water in it now.

 

So it seems to be after a highway-speed drive that it overheats and boils off water.....

 

?????????????????????????????

[Datsunrides]

If it is only doing this after a high speed run, chances are the radiator may be plugged just enough that it won't affect in town running, but can't flow enough at high speed. You can easily check this by feeling the radiator for cold spots after a freeway run. Should be evenly hot. If you feel cold spots, that is a sign the radiator is plugged in that area. Also may want to replace the rad cap 1st just incase the existing one is not holding pressure. The cooling system needs some pressure in it, otherwise it could possibly create enough of a vacuum at high speed to collapse a hose and cause the overheat.

 

mark

[SUBARU3]

I agree....

 

The radiator is most likely clogged. Is it the original? They are pretty inexpensive to buy. I bet that is the issue.

 

Also, consider adding a coolant recovery/overflow tank.

 

Todd

[ninefourteener]

Thanks..... I'm going to go pick up a new cap today (just in case).... and I'm also going to do a chemical flush on the cooling system. I guess if I need a radiator (yes, it is original)... I'll buy one... I'll try to flush it first though.

 

Maybe that will work.

 

I'll report back.

[Rust]

Burp it, before spending $ on new parts.

[ninefourteener]

Well..... it is still over heating at highway speeds. Driving around at 40-45 mph... it is fine..... all day long.

 

On the highway at 65-70... it overheats and boils all my coolant off in 10-15 minutes.

 

What I've done:

 

1) Chemical Flushed the cooling system..... in 2 different directions

 

2) Burped cooling system.... twice

 

3) Bought new radiator cap.

 

4) Installed new thermostat

 

5) Re-checked thermostat to ensure I didn't put it in backwards

 

6) Installed overflow resevoir... it fills when the car gets hot... and refills the radiator when the car cools down.... works perfectly.

 

7) Installed a dual-electric fan assembly, temp sensor and autromatic relay... works perfectly

 

....... and it still overheats.... but ONLY at highway speeds. It is absolutely driving me nuts because this thing will idle ALL DAY LONG in the driveway without overheating. And, I've been driving it for a week around the base at low speeds (40-45)... and it does just fine.

 

..... Oh..... and I still have no heat???????

 

Anyway... I purchased a water pump last night.... I'll get that in next week... hopefully that will solve it.

[ninefourteener]

So..... just put in the water pump...... still overheats on the highway.

 

..... and I still have no heat.

 

Anyone have any ideas where I can buy a heater core for a 78 Brat? I keep finding ones for 1980 and up... but not 1978.

 

Need a radiator too I guess.

 

This car is pissing me off.

[Datsunrides]

Ahhh, the joys of owning a vintage car. You probably won't easily find a new core, but if you search around locally, you can probably find an old school radiator shop that will recore both your heater core and radiator (if needed). Maybe both just need a rod out?

 

Mark

[ninefourteener]

Heater control valve..... frozen solid in the closed position.

 

A little acetone... some elbow grease.... and some WD40...... all better now.

 

Still can't drive on the highway.... still need a radiator.

 

.... but at least I have heat.

[biffanyus]

I think ebay had some radiators. Heres a link to one...

 

http://cgi.ebay.com/ebaymotors/77-78-79-SUBARU-BRAT-1-6-L4-RADIATOR-NIB-OE-STYLE-NEW-_W0QQcmdZViewItemQQhashZitem3ca9f5c5e1QQitemZ260549494241QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Edited September 14, 2010 by biffanyus

[ninefourteener]

Yea... The radiator doesn't seem to be "too" tough to find. I get paid tomorrow.. so I'm buying it tomorrow..... probably off ebay.

 

It was the heater core I was really worried about... NO ONE sells one for a pre-1980 brat.... Thank God the problem was the control valve, not the heater core itself.

[Dirk]

What a strange behaviour from a cooling system.

 

I can't imagine why it would fail to keep the engine cool at speed when it can at idle.

 

I think a new radiator is a good idea but my guess is that it will not be the answer.

 

I'm trying to think of other reasons for an engine to get hot. Heres what I have so far:

 

1. Drag. I wonder if the transmission oil is too thick?

2. Timing. Retarded timing tends to warm things up pretty quick. Are you sure you are getting full advance from the dizzy?

3. Fuel mixture? Is the engine running too lean?

 

Just my thoughts on the matter.

 

Just out of interest are you happy with the performance of the engine at speed?

 

I would like to know what your spark plugs look like just to see how enginge is running.

 

Cheers.

 

Dirk.

[crizzlE]

can you post pictures of your dual fan assembly and wiring system (w/ temp sensor etc.)? I'm thinking about doing this, and am curious. if you don't want to because of the effort, its not a big deal

[78brat]

So she's on the road legally now . I have been driving her for the past couple days and she is doing well . last night I took her on the highway for the first time . still overheating venting steam out the radiator cap .

 

i have changed the thermostat . i have added the dual fan system . everything seems to beat working perfectly . Except still venting steam out of the radiator cap .

 

it seems to be a bit worst when i turn on the heater .

 

Suggestions?

-- Submitted via my HTC EVO 4G

 

have you checked your thermostat?