V50 Overheating (?)
 

Hi! I’m a college student and I just bought an 07 v50, and I’m really new to a lot of car stuff. Recently it’s been giving me some issues, so I was wondering if anyone here had been through this stuff before and could give me any pointers.

a week ago, I was on the highway and I got a “high engine temp- pull over” alert. I pulled over immediately, shut the car off and had it towed. Mechanic replaced the water pump and serpentine belt, and I got it back today. Drives fine, but twice on my commute the needle shot way up, car gave me the same alert, and then a SECOND later the needle shot back to normal. The car drives fine, but my heat was coming out cold like a typical overheat.

Mechanic did say I should replace the coolant reservoir as it had spider cracking, but it’s not very urgent.

I also don’t think it’s the fan, as the first time it overheated today I was on the highway.

has anyone else gotten this issue before? What was it and was it very expensive? Thanks!

Your 07 v50 is one of the few Volvos that does not have a low coolant warning system. As such when there is a coolant leak the driver does not notice it until the high temp message comes on. Unfortunately usually by that point you have a damaged head gasket.

It's possible you simply have a bad temp sensor - but the lack of heat tells me that coolant was not circulating through the engine/heater core. That can be because there is no coolant (it leaked out or was burned in the cylinders) or combustion gasses are being forced into the cooling system through a damaged head gasket pushing the coolant away from the sensor and/or preventing coolant flow. Why was the water pump replaced? It is unusual for the factory pumps to leak. And it's driven by the timing belt. Was that replaced or were the two serpentine belts replaced? Hopefully the water pump was replaced with the factory Aisin brand - there are many aftermarket water pumps for Volvos that are crap, and have seen many fail spectacularly. (pump seizes, belt comes off, all valves get bent!)

For expense - replacing a head gasket where the head is warped (it will be if it was overheated) can cost a few thousand dollars retail.

thanks! Don’t really know why specifically the pump was replaced, but I was told that it was the cause of the issue. The car is also at about 140k miles, so I assumed that was a reasonable milestone for that repair. The timing belt was the one replaced, not the serpentine belts.

Was really hoping it didn’t have anything to do with the head gasket though. Is there any other kind of troubleshooting I can do here? Is it ok to drive a short distance in order to put more coolant in? Thanks again for giving me a better idea!

If it's using coolant just put tap water in, it's free. (as long as you are not in a climate where it is expected to go below about 25 degrees). Everything you put in will be emptied and thrown away when the leak is fixed. And if it's using coolant - and you don't see it leaking onto the ground - it's going out the tailpipe through the head gasket breach.

There is a Head gasket leakage tool that samples the air in the coolant bottle - for HC, unburnt hydrocarbons. the only way that get into the coolant bottle is a damaged head gasket or a cracked head or block. I have heard that is a tool that some auto parts stores loan, but you have to buy the HC sensing liquid that goes in it.

It's possible that the shop just didn't bleed the system after repairing the water pump (and replacing the timing belt, which was overdue anyway). That can cause a low coolant level, which can cause odd things to happen with the temperature gauge and heat (pretty much what you're seeing).

I believe that the way to bleed the system (though I could be wrong - it's been a while since I sold my V50), you run the car with the coolant tank cap off until it's fully up to temperature, adding coolant as it disappears into the "system".

And yeah, replace that tank - plastic is cheap, engines are expensive. ;-) You really (!!!) want to know if you have a coolant leak somewhere else, or if a new tank fixes it. You won't really have a clue until you replace that tank. A quick check on Rockauto.com shows that they cost all of $13 - 24 (at least for my V50 - could vary a bit by year I suppose).

thanks! That’s a huge relief, Really hoping this is it. I checked the reservoir and coolant looked old, but not dirty! Also not experiencing white smoke or visible leakage, so I’m thinking my head isn’t totally blown!

Still did not want to risk a drive, but I was on campus with no other way home so I took it to take 5 and had coolant flushed. Drove for a good hour after with no overheating, but my heat still won't stay hot for some reason. I can live with that just as long as it rolls!

I'd try making sure the system is properly bled, and you might just get your heat back.

I don't think the V50 has a heater control valve (basically, a mechanical valve that shuts off hot water to your heater core, or opens it up, depending on the temperature setting). These are always easy enough to spot (several hoses into/out of them running into the center of the firewall, usually with a cable or module controlling them). If it's got one, just make sure that the outlet hose is getting hot with the temperature set on scald.

When you replace a water pump you drain every bit of old coolant (antifreeze and water mixture) out. Your coolant should look brand new! And those systems bleed themselves easily, the cars with the reservoir close to the firewall. The 91+ 850, svxc70/80s do "burp" after warming up and require a coolant top up.

The car is new to you and someone could have put leak stop in the cooling system partially clogging the heater core. There is no heater valve on that car to stop the water flow - After the engine is warm the pipes to the heater core should be hot all the time no matter if you call for heat inside or hot.

Oh crap. It doesn’t look like a milkshake though, it’s just the usual yellow color? Would the coolant flush have resolved the top up situation?

also, at this point, I have been driving it around for a good 2 hours at least. Should I stop and put like a head gasket sealant in it today? It is my daily driver, and I can’t really afford to take a day off tomorrow, so I wanna at least get it as safely driveable as I can. Thanks again!!!

All a head gasket sealer will do is take money from your wallet (that you could use for something you need - like food) and put it in the wallet of someone else.

A head gasket sealer will not fix a damaged head gasket - if you have one. Volvos with damaged head gaskets don't look like milkshakes in the cooling system. That comes from oil mixing with the coolant and the oil passages on a Volvo engine are too far away from the coolant passages for that to happen. Other brands of cars that happens - but not on a Volvo.

Monitor your coolant level and go from there. Top it up with plain water if it goes down (and you are not in a climate with below +20 degree temps) If it continues to use coolant and there is no external leak, figure out where it is going.

Okay I got it. I’ve been checking under for leaks and checking the reservoir pretty steadily, and it doesn’t seem like I’m losing any coolant. I called up the garage and asked for their opinion and they think it’s one of two things:

One: the thermostat that I DID just replace is defective, and is not opening until the engine gets really hot. I bought the thermostat and housing from a really cheap website, so they’re not premium parts. But they did last through two massive road trips before the overheat, so I thought they were fine. It seemed to me that overheating could certainly damage a thermostat, but garage didn’t seem very sure of that.

Two: my coolant reservoir is not capable of holding the 15lbs. Of pressure that it needs to hold for my car to run correctly, and I need to replace that sooner than originally thought. Garage also did say that they’re “fairly confident” my head gasket is not the problem, since the car starts up normally and I haven’t had it shut off on me/lose power.

at any rate, I’m hoping this thing is still relatively safe to drive, as I took it in to school this morning and I rely on it as a work vehicle (I’m a delivery driver.) that being said, I’ll try to stay off the road as much as I can. Is there anything else I should look for/do at this point?

hey! I’ve heard a couple different things at this point, but do you think it’s possible that a loss of pressure in the coolant system would cause the same issues? I don’t think I’m losing coolant anywhere, but from what you’re saying the car is still ACTING like I am. I don’t know too much about these and I’m willing to bet you had yours for a lot longer than me, so if that sounds wrong to you please do point me in the right direction! Thanks again!

There are pumps to make sure the coolant system holds pressure, this is also used to find leaks. A cheap/ bad thermostat could possibly be an issue, especially if it's not opening properly.

thanks! Thermostat has been replaced recently, but I had that done before the overheat so it might just be defective/broken. It was a pretty cheap part so that lines up.

so then the coolant reservoir isn’t likely to be an issue?

Updating this, I was wrong earlier. I am definitely leaking coolant, and the reservoir is definitely the problem. I thought it was just rainwater this morning but there’s a lot of coolant all around it, and around the cap. The coolant level was also VERY low once engine was allowed to rest for a few hours. I was able to top off with water and get it home without any major issues, bought a jug of coolant on the way for any further top offs; and I’m gonna get the reservoir replaced and hope that takes care of this.

If only someone had suggested that... (see post #5). ;-)

i don’t know why I thought it was fine, but yep you hit the nail on the head with that! Here’s hoping nothing else got messed up, and thanks again for your input!

all this stuff is still pretty new to me but I’m working on it :-)