I have a 1999 Volvo XC70. She’s done really wonderful for me, taking me literally across the country and back. Now with 218,000 miles, we’re starting to have some problems.

The issues I’d like to tackle on this post is the overheating.

It’s tear-jerking and getting worse with the Austin summer, and I need it fixed very soon

This is a long post. If you want to just want a vid, this is 2 minutes:

Volvo V70 Symptoms - YouTube

(I forgot to mention the thermostat replacement. And I was corrected: the fan is not Volvo, just the shroud.)

Symptoms:
When the temperature outside is over 70ºF, and I am in stop-and-go traffic, she overheats. Climbing hills and sitting at stop lights exasperates the problem. Using the A/C is basically not an option, as unless I’m traveling at highway speeds this will certainly cause an overheat as well.
The temperature gauge will slowly climb in stop-and-go traffic until the reservoir overflows.
Also, the fan ONLY RUNS AT HIGH SPEED. However, I am unsure if it tuns off at improper times.
In general though, this engine compartment gets HOT. Like, really hot. Today I went out to fiddle with it after two hours of sitting and it was like I had just turned off the engine.

Treatments:
1) Turning the heat on helps, but only to delay the eventual redline/overflow.

2) When the issues started, the reservoir cracked. I replaced it with two used ones and they also cracked. I put a new one in and it is still holding, but the overheating still occurs.
3) I have replaced the thermostat (However, I believe the one I took out was a 185ºF and I put in the “premium” 191ºF from AutoZone… I have been told the 6 degrees shouldn’t make a difference; I hope that’s accurate. Regardless, the issues persisted the same after the replacement).
4) My neighbor mechanic replaced the fan. I think he did this basically because he was out of ideas… The fan that he put on there is undersized. It is maybe a 10” aftermarket fan. I don’t think it ever needed a new fan. Regardless, the issue persists. And now I’m stuck determining if I need a new, properly sized OEM one.
5) I (partially) flushed the coolant system by taking off the drain plug at the bottom of the radiator (driver side) and spraying a hose into the reservoir. (Note: during the refill of the coolant, I dropped that little aluminum lining under the cap into the reservoir and it went into the system… this, like isn’t a real big deal right? Regardless, issue persists the same before as after). The radiator does not leak and looks to be in great shape.
6) One of the hoses was about to burst. It’s the large one near the right side (driver side) of the engine block. Replaced and holding strong. (This was replaced by an actual Volvo mechanic. I took it to him for the overheating issue. He replaced the hose, topped off my AT fluid, greased up my hood-pop lever, bundled the hack-job my neighbor mechanic did on my fan wiring, told me my fan was too small and that when he drove it with a thermometer under the hood, well, it was too hot. Then he gave it back to me, problem still there. He was just one of these solo Volvo guys with more business than he knew what to do with. I got the feeling he felt that to truly diagnose the problem he’d potentially have to spend two days taking apart the cooling system and just didn’t want to deal with it or my limited wallet.)

Ideas:
At this point, I have a few final solutions:

1) Replace the ECM ECU Computer (Ebay: $75). My computer seems to do weird things. Sometimes my Check Engine light or Brake light will come on, but not for long and the codes are always weird. And if it’s having trouble controlling the fan then that could definitely be it.
2) Replace the ECC Blower Motor Resistor Speed Module (Ebay: $40-$150). I found this video: . My fan definitely only runs on high speed. So perhaps this is the problem? However, that would mean it should have trouble warming up, not cooling down… right..??
3) Replace the freaking fan (Ebay: $30-$440). Certainly, a larger fan will help. But again, this problem persisted before and after.
4) Fully flush the system. It’s my understanding that the flush I did was only partial, and that to fully do it I need to take some more things apart. Perhaps the system is gunked up? But, again, the problem really only happens in stop-and-go traffic. Even a constant 30 MPH is enough to cool the engine down.
5) Replace the thermostat again for a 185ºF.
Again guys, as far as engine compartments go, this one gets HOT.

Any other ideas? I’m really doing this baby a disservice because she’s such a beautiful ride and as my only driver on occasion do overheat her.

Not treating her right. Help!

-Scott

 

These problems are tough to troubleshoot a lot of times. However, in your case, it's clear that you are removing a lot of heat through the radiator, and if you drive 30 mph it's okay. So based on that, you need to go back to a Volvo fan, and blow that heat away. This is obviously the immediate problem. You need to pay careful attention to fan operation. Is it turning on at the right time?


Personally I worry a little bit about the heat generation, because I have the sense that my cars don't have much of a tendency to overheat. But you're not giving it a fair chance.


The heater blower doesn't have anything to do with it.


How high is the temperature gauge going? What do you do when it gets hot?

 

Hey thanks for the response! What do you mean when you say I'm not giving it a fair chance? What part?

And the temperature gauge will get all the way up to past the second red line if I let it, but usually when it starts creeping up I will blast the heat, roll the car in neutral, and turn it off at stop lights just to keep it in the top 3 quarters.

If it gets overflowing and water vapor start coming out of the engine compartment, of course I stop and pop the hood.


*One thing I forgot to mention! If it gets above 3/4 of the way up, the car will become permanently stuck in 1st gear. I can accelerate only to 30 MPH and the RPMs will be around 2700. I have to stop and let it cool off before the transmission will begin functioning normally. I have assumed that this is some safety feature to keep you from running your car at high speeds with a hot engine, but in my case it's actually very frustrating because I know that if I can just speed up (e.g. now that the traffic is loose), she will cool off* Thanks!

 

If the radiator is good, the thermostat is new and the heater works then the only other thing in the cooling system that can be at fault is the water pump (could be spinning on its shaft etc). If that's good, then you need to think about what can cause the engine to sink too much heat - head gasket, turbo pushing combustion gasses into the water or engine misfires come to mind. The ECT sensor gone bad can give false positives but given you are seeing boil overs, I'd be leaning towards a head gasket (try doing a coolant HC test), a turbo issue (any oil/water muddiness? any check engine light?). Is your cooling system pressure is high even before the temp spikes?

 

Thank you. I'll be checking to see if there is any fuel in the coolant today. The oil looks fine. There IS a Check Engine code, but it is for the cat converter not cleaning the air well enough. I was told CataClean is a good solution for this.

 

hmmm, if the cat is clogged it could add to heat build up. Are you sensing any power loss? If you can get at the front O2 sensor, what happens if you pull it out to vent the exhaust - does the engine seem to run better? Maybe time for a new cat - will run you about $500 but at least you get a new flex pipe and its an easy install (unless you build your own or try to buy one from a yard)

 

I plan on cleaning this out with seafoam. Never heard of it, but then angel mechanic who came by and fixed the wiring on my fan (and the overheating!) said it would clean all of that gunk out.

 

Are you planning to use Seafoam in the intake or in the oil to clean sludge deposits? Seafoam is essentially an oil based detergent so it will break down deposits in the oil passages and can remove build up on valves and piston crowns. Not sure if that will help or harm the cat. Check out RobertDIY's vid on Youtube. Good news on the fan being a wiring issue. Sometimes we all overthink the problem space...

 

Did you check for debris build up between the radiator and intercooler/AC condenser?

Kind sounds like air flow is restricted. The cooling fans should suck cool air from the front of the radiator not blow hot air from the engine and against the natural air flow from driving.

I would think using a leaf blower or compressed air and blowing it through the front and feeling the air flow on the back side would work for a test. Maybe clean the ground under the car or put down cardboard so you can see if crap is blowing out while you're check air flow. Visual inspection might require removal.

 

The guy who fixed my fan was planning to use it in the intake. Definitely don't want to harm anything..... is that a concern??

 

Good question. I'll give it a blow just to make sure i have excellent air flow... and triple check that the fan is spinning the right way. But, in general, she's been running really stellar since the wiring in the fan was fixed. SO GRATEFUL! Praise God, and that Check Engine light is even gone!

(But, seafoam still sounds like a good maintenance idea, yeaH?)

 

depends on how he plans to inject it into the intake. If he uses a vacuum line to suck it in and it goes through the MAF, its conceivable that it could mess up the fine grid wires (which is why you should use MAF cleaner vs carb cleaner to tidy up a MAF sensor). If you suspect you have dirty injectors you can use a gas tank detergent additive as an alternative (most gasoline brands already have detergent so its a question mark in my mind as to the value add).

 

Good to hear it's fixed.