Car overheating, not leaking coolant

Tiny
LIAM777
  • MEMBER
  • 2010 VOLVO S80
  • 3.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
I have a very nice Volvo. I have an overheating issue that I cannot seem to figure out. I'm baffled. I could use someone who knows more than me. I could be way off on my reasoning.

Issue:
1. Only in stop-and--go or standstill traffic (or at idle), my car is running hot or overheating. It varies on how long it takes. It does not happen when the car is steadily moving (even at low speeds).

Symptoms:
1. The indicator will say to reduce the speed as the car is running hot.
2. I am not typically losing coolant.
3. When I start to drive, the warning goes away.
4. On a few occasions, it has said that the engine is hot and to stop the engine.
5. When it first started, I could not find a leak and added a bottle of stop leak. Dumb, I know. No lectures. But, it stopped overheating for about a week.
6. When the stop leak did not solve it, I drained but did not flush the system. (The coolant looked new.)
7. With the fresh coolant, I added an additive that also contained stop leak. No lectures. I ran the car at idle with the heat on high for more than two hours while continually gauging the coolant level. No issue with overheating. This too stopped the issue for about a week.
8. Both times I added stop leak, I ran the car pretty hard and replicated situations where it was overheating for an extended period of time without incident.

Eliminated issues:
1. I tried a new cap. Was not it.
2. The indicator is working. The car is running hot.
3. It's not a head gasket. Again, I've only lost coolant if it was actually running hot and through the cap. I'm not losing coolant.
4. Again, it is not a head gasket. There is no oil in the coolant or vice versa.
5. It can't be the thermostat stuck closed, as it would overheat on the highway.
6. The thermostat can't be stuck open, as it would run cool.

Possible but unlikely items:
1. A bad water pump could be the issue. But, it makes no sense that stop leak temporarily stopped and slowed the overheating under the same conditions.
2. For the same reason, I don't see the coolant temperature sensor being the culprit. Stop leak would have done nothing to affect the issue.
3. While I could try a different cap in the assumption I got a defective one, it would not explain the temporary stop leak fix. It's a closed system with the cap on the reservoir.
4. I don't think it's trapped air, as it's self bleeding and was an issue before I replaced the coolant.

Only possible thing I See:
1. Could it be a leak in the upper reservoir tank? It's a closed system. It has a two-piece plastic reservoir that is factory fitted together. The seam is just above the fill line. There are no visible cracks.
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Sunday, August 18th, 2019 AT 8:35 AM

18 Replies

Tiny
KASEKENNY
  • EXPERT
Hi,

Did I miss something about the cooling fan? Usually, when a vehicle overheats sitting still but not moving it is because the fan is not coming on. You have a cooling fan control module so that could be the issue as they normally burn up and cause this issue. Turn the A/C on max with the engine on and see if the fan comes on high. If not, I suspect this is your issue.

If it is not the control module, it could be the fan motor itself. Here is the procedure on how to replace the fan assembly in case you need it. Let me know what you find. Thanks
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Sunday, August 18th, 2019 AT 9:11 AM
Tiny
LIAM777
  • MEMBER
I meant to include that both cooling fans are working. I'm mystified. Thanks for your reply.
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Monday, August 19th, 2019 AT 6:34 AM
Tiny
KASEKENNY
  • EXPERT
Okay. If the fans are working, what happens when it starts to overheat at idle and you rev the engine and hold the RPM around 2500? Does the engine temperature come down?

Normally, when you start driving and it cools down then it is a fan issue. However, it may be an RPM issue which would point to a water pump issue or possibly an air pocket. I would suggest using a funnel like the picture attached. Using something like this will allow the engine to work out the air pockets and leave you with a full radiator.

If you have no air pocket, the a water pump would make sense if the holding the RPM higher and the temperature comes down. Let me know and we can go further if needed. Thanks
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Monday, August 19th, 2019 AT 4:47 PM
Tiny
JORGE S
  • EXPERT
Hi! Just to jump in, with all that stop leak added to the cooling system you may have a restriction in the radiator now.

Another issue could be a head gasket issue even though you stated there is no oil or coolant mixing? I would recommend a block test either way just to rule it out.

Another issue could be the temp gauge reading inaccurate which a simple software update or replacing the temp sensor should take care of the faulty reading. Base on your symptoms it would indicate a faulty fan control module, a plugged radiator, or software issue.

Get a scan tool that reads live data and see what the computer sees when it is overheating. Post a video of the temp gauge or warning message it is overheating, with you still recording show us what your scanner reads as far as temp and walk over to the fans to see if they kick on and show us the expansion tank (coolant bottle) to see if it is fool or ready to explode and that should give us a better idea what we are working with. Thank you and hope to see the video soon.
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Tuesday, August 20th, 2019 AT 12:29 AM
Tiny
LIAM777
  • MEMBER
Thanks. Interesting feedback. I never considered a software update. Is there any merit to the idea that it could be my expansion tank? While I concur with everything you stated, the fact that stop leak helped to some degree has me baffled. Case in point, I live just outside Washington, DC. Worst traffic on planet earth. Five days after first adding stop leak (with zero issues) on a Friday afternoon, I went from Alexandria, VA to Rockville, MD in standstill traffic. It should have been a 45 minute trip. It took over two hours. I had no issue. That evening, I was at a traffic light in DC. I got a high temperature warning. The stop leak definitely did something. I know stop leak is dumb. The symptoms have not changed. I'll look into the scan tool. Thanks for that. I can tell you that when the temperature indicator says that the engine is hot, the coolant level is volatile and rises up and down by about half a centimeter.

The expansion tank came to mind for a reason. After I thought I fixed the issue, it reappeared. I pulled over. After close to 30 minutes, I slowly opened the radiator cap (it's on the expansion tank). It was still hot. I got a steady stream of coolant spilling over. It appeared to be coming from the side and not the cap. There was coolant on the ground. There was no moisture on the top of the reservoir. See pic of the tank assembly.

Thanks so much for your advice.
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Tuesday, August 20th, 2019 AT 6:44 AM
Tiny
LIAM777
  • MEMBER
I'll see the next time it happens. I'll rev her up. Unless the fans are not running optimally, they are not the issue. They are definitely operable. I hear them. I manually checked them. I guess it is possible that they are not coming on at the right time. The water pump was my first idea. Hope not. That includes the timing belt. I just don't think either are the issue. Stop leak twice temporarily fixed the issue.
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Tuesday, August 20th, 2019 AT 6:54 AM
Tiny
JORGE S
  • EXPERT
Sorry my friend, the 3.2L engine does not have a timing belt. It actually is a chain in back of the engine. The power steering pump drives the water pump.
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Tuesday, August 20th, 2019 AT 8:02 AM
Tiny
LIAM777
  • MEMBER
Good to know. Is that better or worst? I used to be a Jeep guy. I could take my Jeeps apart and reassemble it with a blindfold. I'm no mechanic. I'm pretty smart. I kinda get how things work. I truly thank you for your feedback.
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Tuesday, August 20th, 2019 AT 8:11 AM
Tiny
LIAM777
  • MEMBER
BTW, JIS001, if you have that much knowledge, we should be BFFs!
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Tuesday, August 20th, 2019 AT 8:17 AM
Tiny
LIAM777
  • MEMBER
Does anyone have an opinion on the reservoir tank? Does anyone have an opinion on a stop leak additive providing a temporary fix? This issue is baffling. It appears to be something else. Unless it's the reservoir.
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Tuesday, August 20th, 2019 AT 8:27 AM
Tiny
JORGE S
  • EXPERT
The tank is just a sealed reservoir that expands with pressure. You already replaced the cap so I would rule that out. I would like you to do the checks as stated earlier. And yes we can BFF's. As for the water pump replacement, it should take you about half a day to do. The repair manual does not use words but pictures instead so will upload them.

Let us know if you have any questions about the images. Also please do the checks and post videos of the information requested. Also that procedure is to remove the belt. Once you removed all that stuff in the way you can get to the water pump.
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Tuesday, August 20th, 2019 AT 9:03 AM
Tiny
LIAM777
  • MEMBER
So, she started to run hot today. I revved Olivia (my car's name) up to 2500 RPM's. Maintained it. It did nothing. When I drove, slowly, the indicator went off. I have no temperature gauge. I just get a high temperature warning.
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Wednesday, August 21st, 2019 AT 5:17 PM
Tiny
LIAM777
  • MEMBER
Can we agree that it is not the water pump? Or, am I missing something?
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Wednesday, August 21st, 2019 AT 5:19 PM
Tiny
JORGE S
  • EXPERT
I do not think it is the water pump either. When the overheating message came on were the fans coming on at that point? When the message comes on again check the upper and lower radiator hoses for a difference in temperature. If one is hot and the other is cold then you could have a faulty thermostat or from all the stop leak added you may have a plugged radiator as indicated earlier in the post.
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Wednesday, August 21st, 2019 AT 6:48 PM
Tiny
LIAM777
  • MEMBER
Thanks. I added stop leak twice. I drained everything before doing it the second time. I know it is dumb. On each occasion, it temporarily stopped the overheating issue. Thought it was a quick fix. I do not think it's the issue. With 99.9% certainty.
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Thursday, August 22nd, 2019 AT 6:09 AM
Tiny
LIAM777
  • MEMBER
I cannot swear as to the fans yesterday. I can say that the fans are typically engaged. With 99.9% certainty, it's not a fan issue. They both work.
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Thursday, August 22nd, 2019 AT 6:14 AM
Tiny
KEN L
  • ADMIN
Hello,

If I can jump in here. This car has an external coolant pump to circulate the coolant around inside the engine. It sounds like it works sometimes and not others. Here is the location and description of the pump operation. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.
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Friday, August 23rd, 2019 AT 12:55 PM
Tiny
DOCFIXIT
  • EXPERT
Hey just one question what became of testing for co2 in coolant system?
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Saturday, August 24th, 2019 AT 10:12 AM

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