Still overheating even after water pump

broken08 · Post by **broken08** » 14 Nov 2016, 12:18

I have a problem to help challenge your mechanical minds!

I'm a firefighter living in the mountains just west of Denver. I have a 1998 V70 awd with the turbo at 130,000 miles. I do have a larger turbo and injectors plus a tune from ARD; all new, quality parts. I have an issue with overheating that I can not figure out. It will idle all day just fine somewhere around 200-220, the fan kicks on at 217 and off around 205. I tested both fan speeds to be working via grounding the relay, although I can't say I've ever witnessed the fan going in to high speed.
The problem is that on any long, sustained climb or sustained acceleration, even moderate to low, the temp will just creep up. And by up i mean 230, 240, I've even seen 250s, at which point my cap starts to spit out my coolant as expected. I assume that's too hot for it to run?

I replaced the thermostat, I've flushed the system with water, also the coolant flush addative where I drove about 20 miles, I replaced the ECT sensor, generic. If I put a hose in the upper radiator, water will come out as fast as I can put it in out the bottom hose, so there are no restrictions there. I have hosed out the fins of the radiator (which is of course behind the intercooler) and neither look dirty. I can see a flashlight shined through it.

I have pressure tested it to 20 pounds which it holds well for at least an hour. The pressures don't increase on startup so there doesn't appear to be a pressure leak from the head gasket in to the cooling system. The plugs are dry after pressue testing, there is no smoking on startup. I'm running 50/50 of old school green antifreeze and distilled water.

I gave up and took it to a shop, he said there were no combustion gas leaks so the head gasket is intact. He theorized about the water pump not working, which I didn't think would be an issue. They wanted $1200, so I did it myself. I could not see any issue with the old pump or belt as I guessed.

Now it runs great, and it maybe cools a little better, but on a sustained climb up a mountain road over 10+ minutes the temps still crept in to the mid 230s before I gave up and turned around to head back downhill, where it cooled to 195 within about 2 minutes.

So I'm at a loss. I know the only thing left to try is the radiator, but that looks to be a good bit of work with the trans lines in there, and frankly unlikely at this point since it flushes and light shines through it. Otherwise wondering if somehow the expensive blue volvo coolant would magically make the difference over my classic green (which I know is best for aluminum based on my land rover days).
Is there something else I'm not thinking of?

Post by **jimmy57** » 14 Nov 2016, 12:43

The pull on I70 from Denver to Eisenhower has always had an overheat tendency on turbo cars.
Are you using the highest octane fuel? This is the number 1 culprit. The knock sensors will pick up detonation and retard timing and retarded timing delays max combustion till piston is further down in bore and coolant temps go up drastically. The combustion chamber (cylinder head) has little heat transfer to coolant due to valves and spark plug using up the surface area. When timing is retarded and more flame is occurring when piston has moved down in bore away from TDC then cylinders are more exposed and LOTS of coolant is there to take the heat.

Did this only start after turbo, injectors, and tune were added?

No mods to front of car blocking radiator airflow? (sounds like you likely looked for this already)

If you add octane boost or buy some 100+ octane fuel . Googling for 100+ octane fuel yields Hill Petroleum 6291 Ralston Rd, Arvada, CO 80002 as one source. Some place at 32nd and Wadsworth also shows to sell it.

difflock54 · Post by **difflock54** » 14 Nov 2016, 16:50

Given that your higher temperatures are being reached mainly on hill climbing,higher speeds or heavier engine loading i wonder if the fitting of an auxillary transmission oil cooler might solve your problem.
With the cooling process for the ATF reliant on the radiator alone it must obviously cause the engine coolant temperatures to rise somewhat higher also via the heat transfer.
Food for thought ??

broken08 · Post by **broken08** » 14 Nov 2016, 18:45

sure, that could definitely cause higher core temps. Just not sure what the fitting could have to do with it? Trans seems fine by feel.

Post by **tryingbe** » 14 Nov 2016, 19:03

During those hill climbs, what was your speed and do you have a/c on?

If you were going to buy a radiator, buy the best one there is.
http://www.vivaperformance.com/aluminum ... 0-s-c-v70/
Don't buy the cheap Chinese ones, the engine oil cooler and transmission oil cooler will leak in a very short time.

This was my temperature with the plastic radiator, not even climbing a hill. Just in 115F ambient temperature with a/c on.

I changed my radiator to an all aluminum one (it's thicker and holds more water), I have not seen that temperature, even when climbing a hill.

Post by **precopster** » 14 Nov 2016, 19:39

Interesting reading. You certainly have tried all the usual fixes. Well done on passing up the $1,200 water pump (usually a sub $500 repair at an indie repairer)

There are temperature probes that you can buy to see if radiator efficiency is the issue. You can install one pre and post radiator to see if there is a substantial temp drop. The heat transfer from ATF fluid on mountain pass driving that difflock discusses is a valid point. If you install an ATF cooler and totally bypass the one in the radiator you can discount that totally as a cause. B & M produce good examples.

The fuel rating may also be key to a solution. Tunes and standard fuel just don't mix regardless of the quality of parts.

Post by **rspi** » 14 Nov 2016, 19:41

broken08 wrote:
I replaced the thermostat,...

Where did you get the thermostat? Lately people have been buying thermostats that DO NOT fit in the housing causing the car to run hot.

Post by **rspi** » 14 Nov 2016, 19:46

Go to 4:23 here...

broken08 · Post by **broken08** » 15 Nov 2016, 06:37

I have the shorter thermostat, but great thought to check, thanks. Interestingly, when the fan turns on in the driveway, the air it pulls through the radiator doesn't feel warm at all. From other car's I've noted that air should be hot hot hot. So I think that leads me to believe the radiator is not transferring heat well for whatever reason. So on to that. Though in curious if your air feels hot

Post by **erikv11** » 15 Nov 2016, 09:08

On my cars, if the engine is warmed up, the air pulled through the rad feels hot. But of course it must be fully warmed up.

If the rad is partially blocked, that would fit everything mentioned except the easy flow of water through the top. But I feel your pain swapping the radiator should not be a diagnostic move. Puzzler. Maybe try the octane boost see what happens.