308 temp issues

Cleaning up your cooling system helps the non QV cars.

The QV cooling systems were underengineered from the factory. That is why rodding and lower temp switches don't help us much.

If you have one you just eventually get used to it. I just plan road trips more carefully and I don't even really pay it any attention anymore as long as I manage the driving in this fashion

 

Agreed. I've been up & down this path. Sitting in bumper-to-bumper traffic terrifies me watching the gauge go red-line. And here in NNJ, there's LOTS of this type of traffic.

 

This is me in Atlanta. I live in Bham so Road Atlanta and seemingly every car event I attend, is the other side of Atlanta which means I have white knuckles every trip there and back on that downtown stretch of I-85. I have had some rough moments in the beginning but now with the technology we have, not available to us 20 years ago, I can dodge it when necessary (mostly).

Careful navigation trip planning has worked much better than a lower temp fan switch and a bigger radiator on my 84 model

 

No cooling problems if everything works as new. Check the water thermostat and, above all, remove and clean the water radiator (or rebuild the core). Water temperature never has to go above 90 C

 

I still stand by that quote I wrote 2 years ago. I had the radiator cleaned about 4 years ago now and still no over heating problems. The radiator shop said it was full of sludge.

 

Even with the lower temp switch and all fan relays replaced just to be absolutely sure my car was still running crazy hot. Had the radiator pulled and flow tested... Almost no flow. I wish the radiator shop had gotten some pictures of the junk inside.
Mechanic said the fluid came out clean so didn't see the need to flush the block.
Had the radiator re-cored. Now on the highway in hot weather (90F+) temp stays a half tick below the 195 mark. A good start.
Cruising around town with the AC at full blast (>90F the other day) the temp creeps up to a bit above 195 and stays there. No more steady rise over 230 and me having to turn the heater on full blast to prevent total panic.
Next will be to take it up a mountain climb on a warm day. I see a drive up to Lick Observatory in my future before it's officially Fall here in Northern California.

 

Took a drive up to the peak of Mt Umunhum last Wed. A +3000ft climb at 20-40mph the whole way. No issues with the temp performance at all. So glad I got the re-core done!

 

When I bought my 1980 308 back in the early nineties I had overheating in slow stop and go traffic on the way home with the car. Took it in to my indie shop the next day...one of the two fans had been connected incorrectly so that the fan turned in reverse...blocking air flow rather than promoting it. Just something to check.

 

Actually, T-stats are never on/off. They open/close to variable positions/flow depending on engine temp. At some point they can be closed, they can be partially open, they can be fully open. Per spec, a standard auto thermostat opens at it's rated temp and is fully open 15 degrees higher. IOW, a 180F stat starts opening at 180F. It is fully open at 195F. As has been noted, once a stat is fully opened, it can do nothing for you - it is all up to the radiator./fans

In practice, with a well-designed cooling system, a Stat seldom remains fully open or fully closed. It constantly adjusts the opening to keep the temps within the appropriate range. Some poorly designed cooling systems cannot keep the engine temps at the appropriate level when idling or stop/go traffic at high ambient temps. That indicates that the radiator/fans are not adequate for the job. Keeping an engine cool while at interstate speeds is not difficult for any system in reasonable condition. Doing the same at 100F+ in stop/go traffic is a whole different issue. Ferrari's were, apparently, well known for this problem until the mid '80's.

Re bleeding... If a cooling system needs periodic bleeding, it is because there is a leak in the system. When these cars were new, owners didn't have to take them back to the dealer every few weeks for cooling system bleeding. So if re-bleeding is required, something is wrong.

 

Back to the lower temp fan switch. If there is something that is going to cause the engine to overheat turning the fan on a couple of minutes sooner isn't going to fix it.

 

It is often noted that the radiator in a 308 is small. One of the changes in the 328 was making the nose larger to accommodate a bigger radiator system.

Out of curiosity, this morning I measured the radiators on my 3 cars, confirming that my other two cars have much higher areas of radiator per hp:

1983 Ferrari 308 QV: 28”x13” = 364 sq in = 1.5 sq in / hp
1987 BMW 325i: 21”x17” = 357 sq in = 2.1 sq in / hp
2003 Honda Pilot: 30x22 = 660 sq in = 2.8 sq in / hp

Several people have installed thicker or different (e.g. sideflow) styles of radiators and have reported improvements in cooling. While this undoubtedly is helpful, I also wonder how much the airflow through a stock radiator can be improved.

I am currently following a series of articles by Rob Siegel on the BMW CCA website about a/c, but the articles include extensive descriptions of radiator fan selection. Mr. Siegel is an advocate of Italian-made Spal fans, he cites Spal saying, “…They recommend minimum ratings of about 1,250 CFM for a 200 to 250-hp motor, about 2,000 CFM for 400 to 425-hp motors, and 2,500 CFM for more powerful motors.” That would put a 308 as needing a bit above 1,250 cfm to keep it cool.

Both radiator area and airflow are needed to dissipate engine heat, but presumably less radiator area can be offset by higher airflow rate and vice versa. On the air intake side of a 308, radiator air must pass through the car's narrow front grille (52”x 3 ½”) and three lower openings (each 9”x 1 ½”) which is a total of 226 sq in. The outflow side is hard to measure since air exits through both the three hood vents as well as the wheel arches.

I wonder what two of Spal’s finest pusher fans would do for the 308’s cooling. (Spal 30102045; 1,682 cfm each.) I wish I could somehow measure the amount of airflow the stock 308 fans are providing. Just putting my hand to the vents, it doesn’t feel like much. Unlike anywhere else in the car for anything else, there is actually some room up there for deeper fans, but they would need to suck the air through that 226 sq in opening… and the Spal fans draw 22 amps each.

I have caught myself overly worried about water temperature. The Ferrari 308 water temperature gauge is an old fashion “untempered” gauge. It shows the honest temperature of the water; unlike modern tempered gauges which stay at “Normal” until they jump to “Hot” just as the coolant is about to boil over. It is unnerving watching the needle rise on a 308’s water temperature gauge, but too-hot is when the needle is almost pegged to the right.

I had my worst experience in the 308 was returning from Monterey Car Week in 2014. I hit stopped bumper to bumper traffic just south of Gilroy. It continued for 7 miles and took one hour. (Apparently, we all needed to slow down to grieve a big dead dog at the side of the road.) Air temperature was in the mid 80s F. I had the a/c off and the heater on full blast. Somehow I made it without needing to stop or take a run on an open side road.

 

If anyone of you are interested by a Wahler 4033.82D thermostat, there is one still for sale on this Ebay link:

https://www.befr.ebay.be/itm/TERMOSTATO-REFRIGERANTE-COOLANT-THERMOSTAT-WAHLER-PER-FIAT-FIORINO-UNO-4033-82D/224064611450?hash=item342b4aa47a:g:J20AAOSwmkFe~I7T

Regards,
Frederic

 

Only one bleed location on the early 308s..at the front radiator...

Will be watching as I have this same issue now, after chasing a lot of the items mentioned above.

Alan in Houston Texas

 

Thanks I bought the last one...

Those are $200USD at the dealer, here....