Water Temp....Running hot!

**jimshadow** · #1 05-24-2007, 10:22 PM

I've noticed on the past two drives that the water temp will start to creep up towards the 3/4 mark and then drop down quickly. I'm assuming that the fans are coming on at 195* and kicking the temp back down. This has happened sporadically both at highway speeds and at stop lights/waiting for trains... On my last long drive, it happened twice, once on the way down and once back.

Today, however, the water temp was running warm and staying up there at the 3/4 mark and twice it went just a little higher, almost to 120c. This whole time the oil temp was pointing straight down at 100c... I'm guessing at 2 potential problems... 1) My fans are malfunctioning and 2) I need to bleed the cooling system.

When I got home, I opened the engine bay and I could hear the coolant "percolating" in the expansion tank. I could not tell any leaks and there was no overflow...Fans were not running. Motor was definetly hot!

Any thoughts?
If you are adding coolant/water, what is the reference for "full" in the cooling system on these cars?

TIA,

JIM

**rw328** · #2 05-24-2007, 10:49 PM

if the temp gage goes slowly to the 3/4 mark without stopping, and then goes down in the 195 range I would suspect that the T-stat is stuck or not opening at all.

**jonesdds** · #3 05-24-2007, 10:58 PM

Quote:

Originally Posted by rw328

if the temp gage goes slowly to the 3/4 mark without stopping, and then goes down in the 195 range I would suspect that the T-stat is stuck or not opening at all.

+1, I assume it was replaced with water pump at last major? If so, why failing. If not, should have been.

Jeff

**jimshadow** · #4 05-24-2007, 10:59 PM

The water temp will run at 195 or less for a long while, then it will creep to 230ish or so and then quickly go back down. That is what had me to believe that the fans were coming on to cool it down. Tonight, it just drifted right up to 220-230 and hung out there, only dropping to 200ish a couple times...

BTW, the rad was rodded and the water pump rebuilt last year....

JIM

**jimshadow** · #5 05-24-2007, 11:00 PM

Quote:

Originally Posted by jonesdds

+1, I assume it was replaced with water pump at last major? If so, why failing. If not, should have been.

Jeff

I'm going to dig out the records and look...

JIM

**nathandarby67** · #6 05-24-2007, 11:30 PM

My guess would be thermostat number one, and water pump number two. Totally different car, but my Trans Am acted in a similar manner a few years back when the water pump was going out. However, seeing how your pump was just rebuilt, I would try swapping out t-stat first.

**jimshadow** · #7 05-24-2007, 11:42 PM

Any ideas on what the '74 308 Thermostat cross references to??? Would the VW Rabbit one work that is listed in the sticky thread?
I'll pull it out this weekend and have a peek...

JIM

**Tillman** · #8 05-24-2007, 11:45 PM

My 328 had a similar issue. Turned out that the cooling system was losing pressure due to a failed hose clamp. Check your clamps, and you might want to replace your coolant cap with the later 1.1 bar version

**Steve Magnusson** · #9 05-24-2007, 11:49 PM

Quote:

Originally Posted by jimshadow

...Fans were not running. Motor was definetly hot!...

And what about the radiator under these conditions? (Carefully) feel the temperature of the large water line entering the top of the radiator:

cold = probably bad thermostat
hot = probably bad fan motor electrics

**jimshadow** · #10 05-24-2007, 11:55 PM

I did feel the top hose and did not think that it was as hot as it should be....HMMMM!!! Thermostat???!!!

I DO have the 1.1 Bar cap.

I'm going to start her back up tomorrow, let her warm up (Hopefully the rain holds off so I can drive) run the AC to see if my fan(s) come on, check the top hose and do some better troubleshooting. It does sound 'thermostatish' though.

JIM

Perfusion · #11 05-25-2007, 12:51 AM

When you shut the car off after a drive, does it make any groaning noises or sporadic gurgling noises? My car used to do *exactly* as you described, only when I parked it, I would hear noises coming from the car - air bubbles in the less-than-full (i.e., leaking) system.

Check your level when cold in the expansion tank - there is a hash mark stamped into the tank at the "full" level where you coolant should be when cold.

I've found that the wooden paint stir-sticks you get at Home Depot and the like make excellent dipsticks. You can mark them with a Sharpie (doesn't dissolve when wet), and they fit perfectly down in the neck of the expansion tank. Just make sure it's free of any wooden splinters, etc.

Best of luck, Jim.

**Nick** · #12 05-25-2007, 02:06 AM

Bleed the air out of the system first. 90% of the time that is the problem, thermostats do not normally fail on 308's or 328's.

**jimshadow** · #13 05-25-2007, 06:04 AM

Quote:

Originally Posted by Perfusion

When you shut the car off after a drive, does it make any groaning noises or sporadic gurgling noises? My car used to do *exactly* as you described, only when I parked it, I would hear noises coming from the car - air bubbles in the less-than-full (i.e., leaking) system.

Check your level when cold in the expansion tank - there is a hash mark stamped into the tank at the "full" level where you coolant should be when cold.

I've found that the wooden paint stir-sticks you get at Home Depot and the like make excellent dipsticks. You can mark them with a Sharpie (doesn't dissolve when wet), and they fit perfectly down in the neck of the expansion tank. Just make sure it's free of any wooden splinters, etc.

Best of luck, Jim.

After every drive, I open the hood, check the oil and look around. Yesterday I did notice the sporadic gurgling/groaning like you described. I believe that my coolant level IS low. I do not see any leaks, nor have I ever smelled coolant. I'm going to bleed/fill/bleed and see if that solves my issue.

Thanks for all the replies!

JIM

**Hans** · #14 05-25-2007, 09:29 AM

I guess I am lucky

I've got more or less the opposite problem: it will hardly get warm!

Water is always at 80C or so, and the oil just shy of the 100C mark.

During winter it takes 20+ miles for things to warm up at all, and with current summer temps, everything still is 80C/95C as above.

Can't complain...

Hans

Iain · #15 05-25-2007, 10:20 AM

Quote:

Originally Posted by jimshadow

After every drive, I open the hood, check the oil and look around. Yesterday I did notice the sporadic gurgling/groaning like you described. I believe that my coolant level IS low. I do not see any leaks, nor have I ever smelled coolant. I'm going to bleed/fill/bleed and see if that solves my issue.

Thanks for all the replies!

JIM

If your coolant is low and you have no visible leaks then its likely the cap has gone bad. They don't last, get weak & you've just been dropping coolant out the overflow on your way down the road.

When you've dropped enough you start to see air locks in the system & the temp gauge climbing & then falling when you rev the thing. I think you can cook the heads real quick like this so get it fixed & refill the system.

rgds

I.

Iain · #16 05-25-2007, 10:23 AM

Quote:

Originally Posted by Hans

I guess I am lucky

I've got more or less the opposite problem: it will hardly get warm!

Water is always at 80C or so, and the oil just shy of the 100C mark.

During winter it takes 20+ miles for things to warm up at all, and with current summer temps, everything still is 80C/95C as above.

Can't complain...

Hans

Sounds about right - you only worry if you see the thing actually cooling below say 70C on the highway and then only climbing again in traffic. At that point you can be fairly sure your Thermostat needs replacing.

If you Stat is working properly the car should run at basically the same water temperature winter or summer unless you are sitting in traffic at which point the water temp will climb till the fans come on.

Oil temp will vary depending on how hard you are driving - water temp should not unless you REALLY thrash it up a mountain for an hour.

Perfusion · #17 05-25-2007, 12:02 PM

Quote:

Originally Posted by jimshadow

After every drive, I open the hood, check the oil and look around. Yesterday I did notice the sporadic gurgling/groaning like you described. I believe that my coolant level IS low. I do not see any leaks, nor have I ever smelled coolant. I'm going to bleed/fill/bleed and see if that solves my issue.

Thanks for all the replies!

JIM

...and for $6, you might as well go to your nearest auto parts place and ask for a Stant cap (p/n 10229) to replace your existing 1.1bar cap. Even if your current cap doesn't appear to be leaking, it's $6 for piece of mind and having ruled at least one thing out.

**jimshadow** · #18 05-25-2007, 06:12 PM

If I am just bleeding air out and adding coolant to top it off, will 50/50 do the trick? I'll pick up the new cap in a few here...

JIM

**jimshadow** · #19 05-26-2007, 11:49 PM

Ok, so I checked coolant level using the following method:

Cut a dowel to 3', inserted into exapnsion tank and made a line level with the top. Measured down 6cm and marked another line. Then looked at where my coolant level was.....WOW was I low!! Filled tank up to line, warmed car up and checked all hoses and new cap as well as bled the system. Everything checked out so then I drove ~50miles. NO sign of overheating!!!

Thanks for all the replies!! I should be good to go now.

JIM

Darolls · #20 05-27-2007, 01:02 AM

Quote:

Originally Posted by jimshadow

Ok, so I checked coolant level using the following method:

Cut a dowel to 3', inserted into exapnsion tank and made a line level with the top. Measured down 6cm and marked another line. Then looked at where my coolant level was.....WOW was I low!! Filled tank up to line, warmed car up and checked all hoses and new cap as well as bled the system. Everything checked out so then I drove ~50miles. NO sign of overheating!!!

Thanks for all the replies!! I should be good to go now.

JIM

Jim, you're becoming paranoid and overreacting.!

Just check the expansion tank, and if the coolant is approximately 1" to 2"s below the bottom of the filler neck, it's ok.

All you have to do is 'eye' it, like you would do on any car.