98 V70 NA 135K miles - missing coolant

[98v70dad]

My volvo has been losing coolant for the last few months at a rate of about 1 to 2 cups per month. This is an estimate because I haven't measured it.

My car has a new radiator, all new hoses (all of them - even the small ones), new heater core, new coolant temperature sender, new recovery tank (OEM part), new recovery tank cap - non-OEM from NAPA, fresh coolant (within the last year) and a new thermostat. When I replaced the thermostat I think there is an o-ring in the housing and I didn't expect to need one so that one part was not replaced since I didn't have a new one to put in.

I have been watching it for several months and have a few suspects for leaks but they are always dry.

The top suspect is where the larger hose from the recovery tank attaches to the metal line that goes into the block (I think). The metal on that tube is pretty corroded. The galvanizing is gone and the steel is bumpy from the rust. There is a white film there around the end of the rubber hose that indicates there has been some seepage. HOWEVER, I have never found it even damp. I've been trying to think of a way to fix this short of replacing the tube but haven't come up with anything other than cleaning the corroded area with a wire brush. Getting a longer rubber hose and clamping it further down on uncorroded metal would work I suppose if i could find a hose of the right size with the right bends in it.

My second suspect is the old O-ring on the thermostat housing. I don't see any seepage there and I hate taking that off due to the torx bolts being almost stripped. Easy fix though. i just doubt it is my problem and thought i'd ask for opinions.

My third suspect is the recovery bottle and cap. I replaced both of these 5 years ago with volvo parts but my daughter overheated the car about a year ago and distorted the volvo cap badly. She was able to get an aftermarket cap at NAPA and it seems to work. The pressure ratings match. The overheat event caused a lot of visible stress cracks in the recovery bottle. There are dozens of them, but they are all less than 1/4 inch long and they are on the engine side of the bottle. I understand the crack that causes leaks is on the bottom of the bottle or up on the top near the small hose. I plan to drain the bottle and turn it over next weekend to inspect it more closely. HOWEVER, I been watching this for awhile and when I put my hand below the bottle it is never damp. Bottle plus cap (OEM) is about $90 so I'd rather not replace them unless necessary. That said, with all the cracks in the bottle it will need replacement sooner or later.

So regarding the overheating event....it was about a year ago and my daughter was away at school and she called me to tell me that "the little square with a fan on top" on the dash is lit up. I asked her a) is the recovery tank full of fluid and she said YES b) Is there a puddle of green fluid where the car was parked and she said NO and c) do you see any wet areas on the sides radiator and she said NO. So I told her to take it over to only place in town (Advance Auto Parts) which was open and have them look at . Advance also happened to be about a quarter of a mile from her house. I know this because i've spent a lot of time there buying supplies for the V70 while she was in school. At Advance they declared the car OK, but for safe measure I told my daughter to take the car home and park it and I would come up the next day and take a look at it. INSTEAD she drove it about 60 miles and didn't stop until it was steaming from the recovery tank cap. I was really angry but I can't undue whats been done. All of the new parts except the recovery tank and heater core were replaced after the overheat. The overheat was a result of a crack in the radiator at the typical place.

Anyhow, its possible due to that event that I have a head gasket seeping internally. But I've done several oil changes since the coolant level started to drop a little and theres no coolant in the oil. Also, there is no oil in the coolant. Third, the exhaust smells like exhaust .... no sweet smell. i held a rag in the exhaust for several minutes and it ended up smelling like exhaust, not coolant... I've had a head gasket go on an old ford taurus and it was an exciting event. Huge clouds of white smoke and the car barely ran. The volvo is plugging along getting 23 mpg and running like a top, but the disappearing coolant has me a little anxious.

Any comments that would help me focus on what the trouble might be would be appreciated because i'd like to nip this in the bud before it gets any worse.

[abscate]

That white residue is the tell tale silicate deposit of leaking coolant.im guessing you used Prestone or genetic coolant, not Volvo ( that's fine).

I think your fix on the water tube is a good idea but weigh it against adding that cup once a month...

[cn90]

I would send an oil sample for analysis for any trace of ethylene glycol.

[98v70dad]

That white residue is the tell tale silicate deposit of leaking coolant.im guessing you used Prestone or genetic coolant, not Volvo ( that's fine).

I think your fix on the water tube is a good idea but weigh it against adding that cup once a month...

The previous owner used the generic green stuff like prestone and since that was in the car when I got it I continued to use it. When I replaced all the parts in the cooling system I spent the extra $10 and put in the Volvo blue stuff. So those white traces are probably from the old coolant. That's a helpful clue. That tube used to be damp before I wire brushed off all the loose rust when I put in all the new parts.

[98v70dad]

I would send an oil sample for analysis for any trace of ethylene glycol.

That's a good idea that didn't occur to me. Is there a place that can do it economically for a DIY car guy?

[cn90]

FYI, I have been using Green Prestone for 25 years in 1991 Volvo 240, Volvo V70, Volvo S70, a whole bunch of BMW. Zero issues.

In my town, I used Caterpillar heavy machinery company. Any time you see bull dozer, Caterpillar, excavator, combine, farm equipment, you bet money oil analysis is there. This is b/c these equipment cost some $500K- $1M operating in very dusty condition, so the farmers baby their machine. They do oil analysis all the time.

Mine cost $15.

[98v70dad]

FYI, I have been using Green Prestone for 25 years in 1991 Volvo 240, Volvo V70, Volvo S70, a whole bunch of BMW. Zero issues.

In my town, I used Caterpillar heavy machinery company. Any time you see bull dozer, Caterpillar, excavator, combine, farm equipment, you bet money oil analysis is there. This is b/c these equipment cost some $500K- $1M operating in very dusty condition, so the farmers baby their machine. They do oil analysis all the time.

Mine cost $15.

Given a second chance I'd probably go back to the generic coolant. I splurged because all the parts were new and the parts guy at Volvo "gave me a good price". For the time being I'm stuck with it. None of my other cars use the Volvo type coolant and getting something for topping up has been a pain. Next time I'll know better. I searched and found a wix kit for $20 at the local autoparts store.

It will be good to know one way or another if I have a head gasket leak.

I really don't want to dive into a head gasket replacement if it's needed . Although, I'm pretty confident I could do it. I've got a long commute to work and can't be without a car for days. I don't think I could get it done over a weekend. The pcv rebuild took me two FULL days and that's about as much as I want to do.

[erikv11]

I would also check the heater hose coupler on the cabin side, those o-rings can have annoying, slow leaks. Although they usually leak in the winter when it gets cold and they shrink. Look for a white crusty trail down the firewall. And might as well check for crust near/around the o-rings on the heater core while you are contorted like a preztel down there.

Zerex G-05 is almost exactly the same as Volvo coolant, in your shoes I think I would be topping up with that.

[abscate]

I think HOAT and the stuff in non-green coolants still leave white residue in retrospect. Certainly get that joint dry and clean before worrying about the CH gasket. I think your problem is simple.

[erikv11]

Yes they definitely do, no question.