98 v70r: Is this a problem with the coolant res or a HG issue?

[digital.aaron]

So I just got a new-to-me Saffron R this week. I bought it from a fellow Volvo enthusiast who had rescued it from Seattle and brought it back down to Portland a couple months ago. He did a lot of maintenance work on the car, and made good progress to getting it back into shape. He told me that he drove it occasionally to work, and sometimes on the weekend, as he was replacing worn out parts and giving the car a general tune up. However, he noted that usually when the car got up to temp, he could hear a faint hissing coming from the reservoir, and every two or three days he'd have to add coolant to the res. He thought he might have a slow leak in the res, so he swapped in a brand new URO res (although i thought for sure he was talking about a euro reservoir...), but he said it didn't seem to seal at all, so he returned it, and put the stock one back on. He then suspected a bad head gasket was causing the res to get pressurized. So he did a compression test, and all 5 cylinders came back the same. He also did a leak down test, but I don't remember the numbers he gave me. They all sounded normal. Before I left his place with the car, he told me that even with the hissing, and needing to fill the res every few days, that the car still ran dead center on the dash coolant temp gauge, ever when letting it idle for over and hour. 

So of course on my drive home, about half way to my place, I see the temp needle start to climb. i stopped and popped the hood, and could definitely see steam coming from the res cap. I figured that the problem was probably the cap, since that was one item he didn't replace. I ended up picking up a new URO cap and a new res. I first tried just replacing the stock one with the new URO one, but I had the same thing happen. I was driving fine for about 15 minutes, then BAM, the temps started climbing past normal. I popped the hood again to see some water boiling in the res I babied it back home, making frequent stops to let the car cool.

Next, I decided I would try to put a new res in. I got a URO one, and tonight I swapped them out. I put the URO parts in, and took it for a drive. Again, for the first 15 minutes or so, the temp was pegged dead center. I then stopped to see if I could find any steam or leaking water. I saw the engine compartment around the reservoir was wet, but no steam, and no water gushing out of the cap. I decide to continue on my testing run drive a couple more minutes before turning around to head back home. As I'm making my way down the road, I see the temp start to climb again. I pulled over and popped the hood so see water coming out of the cap, and a tiny bit of steam. So I let everything cool down, and then took it slowly back to my house.

So my questions are: 
* Has anyone had a similar issue before?
* Might a Volvo-branded cap and res help solve my problem?
* Does anyone think this might still be a HG issue?

I appreciate any help and/or input anyone can provide.

[erikv11]

Could be the cap, but even a cap made by URO should work fine when brand new.

Next step is definitely to check the cooling system system for traces of exhaust gases, you can get a kit from NAPA or many other parts stores. Could easily be a 1-way leak in the head gasket that is not picked up by a compression or leak-down test.

Other low-probability possibilities: failing water pump, slightly clogged cooling system. Is the fan coming on OK?

[digital.aaron]

Could be the cap, but even a cap made by URO should work fine when brand new.

Next step is definitely to check the cooling system system for traces of exhaust gases, you can get a kit from NAPA or many other parts stores. Could easily be a 1-way leak in the head gasket that is not picked up by a compression or leak-down test.

Other low-probability possibilities: failing water pump, slightly clogged cooling system. Is the fan coming on OK?

​The radiator, hoses, and water pump are all new. The fan is coming on ok, and still runs even if the car is turned off, assuming the temp is still high.

I'm going to grab a testing kit from NAPA today.

[loseR99]

I had this go on my last 99R for a while.  First replaced hoses with silicon samco's, then heater core,  then radiator (twice)  Nissens are garbage (oem one outlasted the headgasket), then coolant reservoir,  then finally the coolant cap.  All oem except for the samco's and my issue went away for almost a year.  

 

Then one hot summer day,  i was hammering down the on-ramp and headgasket finally went,  coolant in number 5.  

Do you ever have white smoke? 

[volvoguy23]

Take your thermostat housing off and make sure the thermostat isn't broke. 

If you had a leak in the cooling system it wouldn't be pressurizing that much. If coolant/steam is boiling out of the cap or resivor it's a clear sign of a bad head gasket. The resivor caps are designed to release pressure if the cooling system pressure gets to high Which is either caused by a major blockage or bad head gasket. Like I said take your thermostat housing off and make sure thermostat isn't broken. It will be closed shut if so causing these issues (hopefully) it would explain the overheating within 15 minutes and high pressures. I'm surprised the thermostat hasn't been mentioned at all. Takes 1 minute to  take the thermostat housing off.

if it's not broken it will be time to pull the head and order some parts.

[digital.aaron]

I had this go on my last 99R for a while.  First replaced hoses with silicon samco's, then heater core,  then radiator (twice)  Nissens are garbage (oem one outlasted the headgasket), then coolant reservoir,  then finally the coolant cap.  All oem except for the samco's and my issue went away for almost a year.  

 

Then one hot summer day,  i was hammering down the on-ramp and headgasket finally went,  coolant in number 5.  

Do you ever have white smoke? 

​The only time I've noticed white smoke (in the three days i've owned the car, lol) is in the morning when it's chilly and the engine is cold. after a minute or two it goes away. Nothing out of the ordinary.

Take your thermostat housing off and make sure the thermostat isn't broke. 

If you had a leak in the cooling system it wouldn't be pressurizing that much. If coolant/steam is boiling out of the cap or resivor it's a clear sign of a bad head gasket. The resivor caps are designed to release pressure if the cooling system pressure gets to high Which is either caused by a major blockage or bad head gasket. Like I said take your thermostat housing off and make sure thermostat isn't broken. It will be closed shut if so causing these issues (hopefully) it would explain the overheating within 15 minutes and high pressures. I'm surprised the thermostat hasn't been mentioned at all. Takes 1 minute to  take the thermostat housing off.

if it's not broken it will be time to pull the head and order some parts.

​Someone on another site mentioned the t-stat. I'm going to pick one up this evening after work. I'm crossing my fingers that it's the t-stat and not the HG. I'm not against doing the work, but I'd rather not drop the cash for the parts and machine work on the head..

[digital.aaron]

I was just reading some articles on how to test a thermostat at home, and one of the tests involves letting the car warm up, then squeezing the top radiator hose. If water rushes in after releasing the hose, tstat is probably good, but if the hose is too stiff, the tstat is probably stuck closed.

I've noticed my top radiator hose is usually very stiff at normal running temperature. I'm hoping this is a good sign of a bad tstat and not a HG leak. I will report back tonight with more findings.

[volvoguy23]

I wouldn't bother, just unbolt it and take off the housing, hose attached and everything. There shouldn't be very little if any coolant in the top hose so if your worried about making a mess just clamp it with some vise grips and a towel. The top portion of the thermostat will be split in half.. Here's a pic of the one I just took out of a friends s70 that was having your exact same issues... It was only like 4 months old. Not sure of the brand can't really see one. 

[troyhyde]

If you have a busted head gasket it is typically easy to tell with a simple sniff test.  On a cold engine, remove the coolant reservoir cap and start her up.  Stick your nose in there.  Smell like coolant (sweet)?  Smell like exhaust (gassy)?

From what you've laid out, I'd say odds are about 95% you have a bad head gasket.  URO parts are horrible as a rule, but it is because they fail quickly (say 1-2 years).  The don't fail immediately.  The Volvo or OEM stuff will go for many years.  I doubt you have a bad coolant tank, cap, etc... 

As a previous poster suggested, remove your thermostat just to verify it is not playing a role.  If it looks okay and the spring isn't broken/frozen you've got a busted head gasket. 

[digital.aaron]

If you have a busted head gasket it is typically easy to tell with a simple sniff test.  On a cold engine, remove the coolant reservoir cap and start her up.  Stick your nose in there.  Smell like coolant (sweet)?  Smell like exhaust (gassy)?

From what you've laid out, I'd say odds are about 95% you have a bad head gasket.  URO parts are horrible as a rule, but it is because they fail quickly (say 1-2 years).  The don't fail immediately.  The Volvo or OEM stuff will go for many years.  I doubt you have a bad coolant tank, cap, etc... 

As a previous poster suggested, remove your thermostat just to verify it is not playing a role.  If it looks okay and the spring isn't broken/frozen you've got a busted head gasket. 

Reservoir doesn't smell gassy.

 

So I got an OE tstat today and installed it earlier this evening before heading out to the movies. On the way home, I decided to take the long way, to see if it still wanted to overheat after a bit of driving. I drove around for about a half hour with the temp needle steady at the half-way mark. At about 35 minutes, I noticed the needle started to climb. It went up two lines (still below the red), but the fans kicked in, and I assume the tstat opened and the needle went back down again. I was happy, but not completely satisfied. I drove around another 15 minutes or so, and the temp was normal most of the time. But it did want to get a little too hot. I checked under the hood during the last high-temp episode, and sure enough, steam and water were coming out. 

To clarify, I've been running just distilled water the last two days, because it's a lot cheaper to throw away a 79 cent gallon of water than it is to toss a $25 gallon of coolant. I think this was part of the cause of the steam and boiling water. Next I'm going to flush the cooling system and add a 50/50 mix to see if I can get the high temps to go away.

I'm still not entirely convinced my HG doesn't have a leak of some sort, though. But this is a step in the right direction.

[BEJinFBK]

FWIW, In normal operation, the temp gauge should hang rock solid at 3:00.

[troyhyde]

Yea, the gauge sort of flat spots between approx. 170-220F degrees, shouldn't move much unless you are getting much higher temps.  I'm almost positive you have a blown head gasket (been there many times). 

I hope you can find a simple fix but prepare for the larger job that may be ahead...