1985 308 Qv, Help!

A couple ideas to discuss or try:
-- have you flushed the radiator again, counter to the normal flow? Could be blockage after the engine flush dislodged some build-up debris?
-- when you flushed the engine water lines out, did you run water both directions? Perhaps you agitated something that dislodged later and is now stuck in a line slowing your flow? Debris starving the pump inlet could lead to significant drops in flow rate and cavitation risk.
-- when the engine warms up and settles around 220, if you turn your heater and fans on full do you see your coolant temp dip? If so, insufficient cooling capacity might be the issue but if not, easily rules out cooling capacity and turns attention back to the cooling management side of the system.
-- since you had the electrical work done, can you check the state of the car ground, or the state of the common line to ground on the sensor line? Could it be that the sensor is giving faulty readings in situ that it wouldn't give outside of the car during a calibration check because the voltage is floating while driving as the vehicle load on the circuit changes? Perhaps turning on your brights or cycling your AC while watching your temp needle readout could see if it's a load/sensor issue.

You definitely have a tricky one here, dude. Ignore any of the above that might be a goose chase as all of my typical diagnosis topics have already been covered either by yourself or others in the discussion. Sorry for your troubles.

 

TR/TR512/348/F40/328/and several of the V12 motors have aluminum sleeves. Why don't they overheat?

 

No, just a new technology from Mahle. Supposed to increase HP and last longer than iron. They did both.

 

Wasn't there a thread regarding thermostats and the outer diameter sizing being too small allowing it to move around and possibly hang the block off disc?

Also, isn't wade in NC?

Have you put your original t stat back in there or physically compared the original closely to these replacements?

 

Chasing cooling issues in my old Qv was a pita... finally a brand new re cored radiator - extra set of rows etc... new water pump, and run water wetter and water kept the car ok for summer here in Atlanta - but the temps would always climb in traffic. once out on the open road it would settle down to just past 195 but then as soon as you stop moving - back up to 220... or more.

with my 328 I usually dont have any cooling issues in bumper to bumper Atlanta summer traffic - I have literally had it out on 100F days and it works well... but even then the numbers will be on notch past 195F... but not like in the QV

that all being said... have you bled the air from the top of the water pump? that can cause a bit of an issue.

also when bleeding and filling up the car - jack the back end up, and fill it that way - also run it up to temp, so that you get all the air bled from the front then work your way back to the water pump... Make sure all the heater elements are on full... it should be nice and toasty in there. checking the actual temps with an infrared gun is good for peace of mind... and last by not least - clean the contacts on the gauge and sending unit...

a new cap, and re bleed i think might work.... I would also suggest you talk to Ron Reinek at sports car service - 404-435-6760...he is your guy to help you out. he knows these cars in and out.

 

I don't get it. 31 years with my 85 and never a problem except when the coolant tank cap wouldn't hold pressure. All original cooling system including the water pump. And I'm not on who changes coolant every two years. It will get up to 210-215 sitting at a light on a hot day but drops down to 175-180 as soon as I get moving.

 

Didn't have a clue. I just remember reading that in C&D when they tested the new QV back in Aug 83.

 

What's with the hostility? I suggested it to be only considered, not carved in stone and carried down from a mountain.

 

When you filled the system, did you use a vacuum pump to pull the air out first? I got this nifty vacuum pump/filler that fits on the expansion tank and hooks to a compressor. You press a button and it uses a venturi to suck almost all the air out of the entire cooling system. It then has a valve that you open to draw in your coolant from a near by bucket. I used it on the 996TT and it worked great and that car is also notorious for difficulty in bleeding. I did the whole process with the nose down the driveway just to help. It pulls such a strong vacuum it will collapse the softer large coolant lines.

I don't know if there would be any issues using on the 308, but it sure worked well on the 996.

Just a thought...

Franny

p.s. I thought the .9 Bar cap was stock for the 308 and the 328 went to the 1.1Bar, no?

 

Maybe I missed it. What were the results of using an IR gun? FWIW I tweaked my inline resister after my rebuild so that 90 C on the gauge matched 90 at the thermostat with IR. Probably a stupid overkill. I am not sure about how well it tracks at higher temps, but at least I have one common point. If I recall right, it did not take a much different resistor but the tweak made me feel good.

This is probably not your issue. Just more background noise.....

 

1.1 bar cap was on the car when I purchased it. I ordered a new cap from Superformance, it was the 0.9 bar cap. I don't have a vacuum system to pull air out of system, but I have seen them. Heaters are nice and toasty. As for timing issues, I timed the cams by the hash marks that were notched into the cams and caps by the Ferrari engine builders. I didn't use a dial indicator to do the job, but the car runs very smooth at idle, and runs like a "striped haint" as my dad would have said. Exhaust system is clear, as there is a cat pipe installed in place of the cat con (will disavow this statement legally).

Basically same operation as above statement; runs at 195 on highway operation, will heat up to 220 or so at idle. Upon resuming highway travel, the temp drops back to 195. My concern is extended idle when stopped, when temp continues to climb to 220 and beyond.

I am going to remove t-stat, test in pot of hot water, then retry. if all else fails, I will remove upper plenum, inspect hoses and coolant tubing, reflush pipes, reflush radiator, and see if I observe anything else. I keep going back to the original condition; I never had any problems until I took this thing apart to do the service. Maybe I did something wrong. I reluctantly refuse to believe that there is a head gasket problem, although anything is possible.

I still plan on replacing the expansion tank cap with the Stant cap. I'm still puzzled, as this car was purchased with deferred maintenance and ran GREAT! None of this occurred until I did all this wonderful service work.

 

I also removed and cleaned all grounds on the car, lights on, etc. has no effect. IR gun shows temp at expansion tank at approximately 195. I even ran a long probe under the plenum to the temp sender; readings were around 180 or so. Same for reading the pipe temps into and out of the engine. I will rebleed system before another tear down. Weather is bad here as of today. 6 inches of ice and snow, so I won't be out on the road until the snow clears. I'll be back in touch soon.

DB

 

I have an 84 QV, and have seen unexplained higher temps similar to the scenarios you describe as well. Not all the time, not as often this past year. I've installed a Ferraripilot aluminum radiator, replaced all the coolant hoses (SRI), replaced every single heater hose (total coolant and heater hoses = 26 hoses, 52 clamps!), installed a new water pump, replaced the thermostat twice (the second one tested on the stove), bled the system front and back multiple times after each change, done an IR temp gun check and pipes showed 190F when gauge showed 220F... fans come on and go off appropriately.

After all that, I don't believe the engine is actually running hot. One other symptom - sometimes the temp gauge will be showing 220, I glance away to shoulder check a lane change, look back (or a similar small period of not looking at the gauge), and the gauge will have dropped to 190, nearly instantly. I suspected sticking thermostat, but I've seen that happen with 3 different thermostats. Other note - any time the temp gauge indicates running hotter (220), the oil temp is still steady under 200. When I first bought the car in 2013, before I did any work on it, on a hot day it was indicating hot, and the oil temp was also hot, I think on that one occasion it genuinely was hotter (but still not overheating to the "at 230, I shut it down" zone)

LAST option - electrical. Defective sender, defective gauge, or bad grounds. Note your quoted sentence above - at idle, the gauge climbs. Also at idle, the alternator voltage or output will likely be lower. Could there be a correlation? In related threads, several forum members suggested that cleaning the connections on the back of the gauge solved their indicated running hot issues; others have suggested that cleaning the wiring harness ground points under the dash has made a difference. I'll be trying those items next!

 

Maby his waterpump is not effective, not pushing water through like the original pump?

If it can be the Thermostat, I would drill a hole through it or make the valve stay open, I'm sure Brian has done this before, let the water flow through directly just as a test, it will take longer to warm up the water but just as a test to see if the max temp reached is lower, if not then he knows for sure its not the Thermostat valve not opening fully or stuck in closed position.

is there a possibility that the oil cooler on the left side is blocked, like mabe oil flow is slower that cause excessive heat ?

regards
Johnny

 

From post 36 I understand it operates as expected when you are moving and only creeps up when you are static. That to me sounds like a heat transfer problem. You had the radiator out, did you put a fresh coat of high heat (or any) paint on it? Did you adjust the cooling fans so they are as close to the radiator as possible? What is your idle voltage? What is your idle speed set at? Having grown up with muscle cars a nice 5-600 RPM burble seemed the natural thing to me at first, factory specs for these cars are much higher; 1000 +/-100. A low idle could cause insufficient coolant flow and insufficient voltage to get the fans up to proper speed.

 

Yep, fresh coat of paint on the radiator. Fans are as close as I can get them.
Also, gauge seems to "mysteriously" drop back to below 195 just about the time you're ready to pull over and shut it down.
Fresh coolant, water wetter also in system. 50/50 mix of old style green coolant.
Same thing; new hoses front to rear. How much fun can one have replacing both AC hoses and brake vacuum/heater hoses on both sides of the car? You haven't lived until you do.

My head is spinning and I'm tired. I will process all and above info, go back to trying a logical troubleshooting approach. An old mechanic (now blind and invalid) told me once that "finding the problem before changing a bunch of parts" is easier than trying to figure out what's wrong after you've changed everything and still have the same problem.

Thanks again to all for your insight and your kindness.

Regards,
DB

 

Almost forgot,

Oil temp stays normal (195 also, well below the 210 mark on the oil temp gauge) even when the coolant temp goes to 220 and above.

I'm with you, I don't think the car is "really " running hot. I've been around enough stuff to know when something is really running hot; boiling over, excessive temps under hood (you can feel it), popping and crackling, steam coming out of overflow tank. I just get a high reading on the gauge. We'll get it figured out guys. Thanks a lot.

 

Did you ever discover what was causing your problem? How would you go about testing your gauge? I think my gauge is off. Here's some pictures. I would say my gauge is showing 105c. My fans come on just a hair before that mark. The gauge will show a hair above the 105c mark and cool down a hair below the mark. The fans go on and off. You can see the oil temp looks good. See the temp at the expansion tank? See the temp at the radiator. the temp at the bleed valve on the engine is 195f. The temp at the lower rad hose is 168f. It was 85f outside and the car sitting still. Crusing down the road at 70mph the temp gauge runs a hair over 90c. It doesn't smell hot. It doesn't boil over. It doesn't burp fluild out. I think the gauge is off. how do I test that.
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May be a stupid response but..... Are your fan motors wired correctly to blow air through the radiator and not reversed? Would explain them going on and off correctly, high idle temps, somewhat normal driving temps. As they are D.C. Motors reversed connections will result in reverse spin. Also there are wrong fan blade (reversed) on the aftermarket that suck instead of blow even when wired correctly. Ran into this myself. Have they ever been replaced?


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They are blowing thru the radiator. Looks like original fan motors and blades. They blow even and hard. I have bled the system many times to remove the air at the radiator and the engine. Are the temps at the expansion tank 195f and upper radiator 189f normal?
It doesn't look like the radiator has ever been out or repainted. I read another thread about the thermostat could be the wrong size. Should be 56mm not 54mm. The other day I order a timing belts, bearings etc a long with radiator cap, thermostat, gasket ,o ring and sending unit from superformance. Just so I have it if I take it apart. May just need a cooling system over haul. I haven't seen where anyone temporary installed another known good gauge to compare. Can you purchase a gauge from a auto parts store and try it?

 

Dave, see my post #38 in this thread - my 84 Euro QV temp gauge acts like yours, and I've done the IR thermometer readings similarly. At this point, my prime suspect is a gauge fault, as I have gone through everything as you are and eliminated pretty much every other factor. The key indicators that it's "just" a gauge problem are the IR readings, the appropriate oil temp readings on the gauge, and the fan running appropriately. I have replaced my thermostat 3 times, and tested them stove-top before the last change.

My next step in chasing this will be to remove the instrument panel and clean the connections to the temp gauge and the ground points under the dash. I'm in no hurry, though.

 

My gauge will fluctuate sometimes like a second hand on a clock, jump back and forth a 1/8 of an inch like yours. Where is the most accurate spot on the engine to test the temp with your ir gun? Correct me if I'm wrong, I think a dirty or bad connection the gauge would read low. Anybody out there have a known good accurate temp gauge laying around? With the sensor and gauge out of the car, could I put the sensor in hot water with a known good cooking thermometer and wire in a 12v battery into the circuit of the gauge to check for accurate. I'm I way off on my thinking or would this work?

 

My temp gauge fluctuates when my headlights are on. When they are on the temp goes up, when I turn my headlights off the temp gauge moves back to where it should be.
On a point re the expansion cap, when I used the 1.1bar my temp would always go over 90 deg C, I have since moved to a 1.2bar cap and the temp hits 90 and does not move from there.

 

Maybe wire in an aftermarket sensor and gauge? Something cheap just to test it?

 

Looking back thru the records on the car the thermostat, expansion cap or the radiator have never been touched. It has been flushed and some hoses replaced. Belts bearing ect been done in the past. When I get my parts next week I will go ahead change about everything. Radiator shop told me $80.00 to rot out the radiator or recore it for $300.00 if the core is bad. Its 30 years old it can't hurt. That's when I might try a after market sensor and gauge as long as I find a sender that fits. I may try the sender and gauge in hot water just to see if it works and what it reads. I wonder when you turn on your lights and the gauge reads higher if the lights are dropping the voltage to the gauge making it read higher. Just a thought.