Mystery coolant leak on V70 T5, 1997

[V70T51997]

It's european model, so that's why it's a 1997 one.

Have had the car for 1.5 years now and it has had the coolant leak for about 8 months now. It didn't leak as much in summer (temperatures of ~20 degrees Celsius, or 68 degrees Fahrenheit), but as the winter came and the cold weathers, the coolant has started to drain some more. Currently it's around -10 degrees Celsius (14 F), but it has dropped down to -30 Celsius (-22 F).

So, I've replaced the radiator last fall. Also, a new thermostat, the lower thermostat housing (stripped/jammed bolts which eventually led to using a "bit more" force and the housing broke down), a new breather tank and the hoses, a new Volvo radiator cap, new water pump, new heater element on the cabin and new oil coolant lines. I've changed new seals to all of those.

The coolant level will stay at max mark currently for about 30 km runs (or ~19 miles). Then it will drop down to a point in which the coolant level warning lamp will illuminate. If I go and rev the engine a bit while driving and then ease up, the coolant level will rise and the lamp will go off. After a couple of seconds it might illuminate again. There are NO obvious leaks, I've crawled under the car and all. I've changed the seal which can be seen in this picture. That didn't help at all. However, after the engine and coolant is at it's normal temperature, there will be some smoke rising from that seals area. I've checked from under the car and with a mirror, but I can't locate the exact spot from where the smoke is coming from.

I've run a pressure test to the cylinders. The readings were (approximately) 11.7 bar on the first cylinder (leftmost), 12 bar on the second, 12.4 bar on third, 12 bar on fourth and 12.3 on the fifth. There might be some rounding off to the nearest full decimal as I've converted those readings from kg/cm2.

The oddest part is that the coolant level might drain overnight, after you've driven the car for a bit to the normal temperature, and leave it to the parking lot. I can't tell whether it will leak it to the ground or wherever the heck. I've tightened the clamps around the coolant lines (under coolant tank, on the water pipe that is connected to the turbo cooling lines etc...) but I've not yet identified that where the leak is.

I've also wondered if there could be leakage through turbo (Mitsubishi TD04HL-16T) but I've been told that it is virtually impossible. Is it? And after taking off the boost pipes, I saw some oil in the turbo housing, not much... Any thoughts on that?

Frustrating as hell, and I really like the car. I already have a head gasket kit that's awaiting for installation and the head will be opened when my brother has the time. Thought to come and ask you guys if you've ever had anything similar problems with your V70 or 850 as they're basically identical under the hood...

Greetings from Finland! And thanks for any answer that might be written.


edit: and the fluids haven't been mixed, although there has been a little "mayonnaise" on the oil dip stick and oil cap, but that's been due to the short trips on cold weather mostly...

[cn90]

Do the coolant system pressure test.

The turbo has a coolant hose at the back of the turbo that can leak.

[drgswede1978]

I have the exact same problem(1998 v70xc). Every time the temp is below -15 c it seems to dump coolant onto the floor. So am very interested if anyone has any ideas.

[V70T51997]

The lower coolant hose on turbo has some oil under it, I saw that when I was inspecting possible leak points. But I will try and find some way to do the pressure test, I do have some spare coolant caps that could be modified so I could use a hand pump maybe...? The Volvo tool for testing the coolant system is way too pricey for a student.

IF the lower hose does leak, what do I need to change? The whole hose? Seals?

[cn90]

- To make the test tool, use the old cap and make a fitting for air compressor.
Set air compressor at 15 psi or so during testing.

Below is the info on how to make a cap. In this case it was a cap for brake bleeding. But you can do the same thing for the Volvo coolant cap:
https://www.matthewsvolvosite.com/forums ... hp?t=29243


- Turbo coolant hose info ($15 for the hose):
http://volvoforums.com/forum/volvo-850- ... ent-59878/

[V70T51997]

Now that you've linked the pictures of the hoses you meant, I see that I didn't mean those. I meant the lower line pipe. But I'll check out the hoses too today and try to get the parts to make DIY pressure tester. Thanks for the useful links!

[T5erry]

I’m going after the low hanging fruit…

If you leak is anything like mine it will be a relatively simple fix; it’s just a matter of finding it.
I’ve got a 99 v70 T5. While I’m not sure how different it is from your 97 euro model I’ll tell you where all my coolant leaks were that I’ve chased for over a year. I’ll also be a bit more detailed in case someone reading has a mysterious leak as well.
I had been leaking coolant for 8+ months before I found my first leak, but it was a short lived celebration. In all I probably had some form of a leak for around two years and had more than one leak at the same time. The amount it would leak, just as yours, would vary by day and week depending on the temps.

First was a heater core going bad. It’s easy to check. Peal the carpet back from under the plastic cover which is to the right of the gas pedal. The cover should slide toward the back of the car and pull out. With a flashlight look to see if there’s any leaks anywhere. Mine was leaking so I ordered a Behr replacement and two aftermarket o-rings. After replacing the heater core/o-rings I drove it around the block/got the car hot and not leaks. I checked it about a week later and it was dripping from the connections. I attribute it to the o-rings being aftermarket. I had held the old o-ring up to the new when installing and they looked identical. I cleaned the old pipe before installing but I guess there could have been some missed trash or metal burr on there I missed. The only way it ever stopped leaking was to tighten the screw up as hard as I could. I’m surprised they didn’t sheer off. It’s not leaking but I dread the day I have to deal with backing the screw out again from all the heat/cold cycles it will have gone through. Tip- when checking for leaks shove a mirror flat up under the heater core; you can see a lot more. Also, a maple syrup smell in the cabin is also a good indicator of this leak.

Second leak was a hair line crack in the radiator that went overlooked for the longest because of its location. It never did leak much and I drove it for approx 4 mts leaking from the time I discovered the leak. You’ve replaced yours so no worries there.

Third leak was the nipple on the bottom of the coolant reservoir expansion tank. Because my power steering reservoir cap had been leaking so long and created such a mess in that area I couldn’t tell there was a leak there even though I had looked numerous times with a flashlight. The nipple probably gets cracked from being wrenched on when moving it out of the way changing the timing belt etc. There’s a metal insert in the nipple to keep the nipple from collapsing when tightening down the clamp on the coolant drain hose. In my case I had a hairline crack in the nipple that would seep but never leak terribly b/c the metal insert was enough reinforcement to hold it together. Because my coolant drain hose was so old (not supple) I went ahead and replaced it when replacing the tank so I wouldn’t have to tighten down so hard on the old hose in an attempt to not crush the new nipple.

A few weeks after I fixed the expansion tank leak and had no change in coolant one day the coolant light came on. For weeks it would come on/off sporadically. The coolant level sensor was bad. Replaced it and problem solved.

Since I’ve replaced the upper radiator hose and the expansion tank hose on top of the reservoir which are pretty obvious if there leaking. Before replacing both of these I actually tried trimming the end off the hose just behind the clamp to get a better seal. While the hoses looked o.k. they just weren’t supple anymore. I kept having to tighten the clamps in an attempt to get a seal and never did. Again, the nipples on the top of the radiator and expansion tank are plastic…better off just putting new hoses on.

[V70T51997]

Thanks for your answer! They are just a little bit different but not by much. I'm gonna try and gather the parts to make a DIY pressure tester and hope that it will help me find the leak. Also, I mentioned it as "heater element" and with that I meant heater core. It has been replaced and the o-rings on the lines also. But I will check that too. There will be a sweet smell during driving and that most likely comes off the engine room somehow when I'm circulating the air from outside in to the cabin.

Will report after I've tried to test the coolant system pressure. But that is great info for everyone else too!

[V70T51997]

I've made a system coolant testing hose, ended up buying 1 m of 8 mm (inside diameter) gasoline hose, a T-link and a tubeless valve. One end goes to the coolant tank and the other end goes to the thermostat upper housing. And in the middle there's the tubeless valve. If you decide to do a similar one, I'd advice that you'd purchase at least 9 mm inside diameter hose, or maybe 10 mm. The 8 mm hose is quite tight although it will expand (mine is braided so I can break some of it and it will allow it to expand more).

I put some pressure on the system, and around 1.5 bar (the pressure meter isn't accurate on my pump) the coolant cap let excess pressure out. So it's working as it should. There was some tiny bubbles coming out of the coolant tank end (where I attach the test hose) as it has broken from time, so that is a tiny leak point but it's highly unlikely that all of it comes through there. I'm 95% sure of it.

I'll have to do more testing tomorrow (take spark plugs out etc) because it's too late for me to see anything outside... Will report back tomorrow.

[V70T51997]

What do you know! I've pressurized the coolant system and found one leak point, but I'm not sure where exactly. It's dripping somewhere above the gearbox (manual) and down there to the ground. I just left the system pressurized and also left a flat cardboard box under the engine to see whether that's the only leak point. One mystery more for you to solve; I have a radiating engine heating element attached on the block and it started to fail last fall. It has a coupling unit attached to chassis right around the center of the windshield line and it's soaked with coolant. There's no obvious way for the coolant to reach the coupling unit, so now I'm wondering how can the coolant be around there? Also there are coolant droplets around the water pump, under the cam belt cover, on the fuel lines that go down from engine top and from there they go under the chassis to the tank, and also there has been coolant drops under the chassis around back seats area! How does it get there?

Taking off the spark plugs didn't release any pressure that I would have noticed. Should have had a stethoscope of a kind...

It's a bit challenging to check the leak points as I have to do it lying on the ground when the car's jacked up (on the parking lot). Started to realize what the saying "chill, dude" means, or feels like (-15 °C and gusts of wind 6 m/s). Would be nicer to do it somewhere warm.