2.5T Blown Head Gasket?

[Griff]

I have a suspicion that my 2004 XC70 has a blown head gasket, but wanted to run some info by the experts here to get their opinion.
What leads me to believe there is a head gasket issue:

- The cooling system seems to over-pressurize. When fully up to temp the upper radiator hose seems to be almost rock hard.

- I have noticed within the last 6 months that it goes through coolant. Not a ton, I probably fill it from the low mark to the full mark once every 2-3 months. I don't see any external leaks - no clear sign of leaking coolant from the radiator, no obvious sign of it coming from the water pump, heater hoses, or heater core either.

- I actually bought the car after the heater core blew (filled the cabin with steam, not just a failure where it trickles out like I have commonly seen associated with failed heater cores) on the previous owner while he was driving. He said he towed it to the shop, but drove it home 1.5 miles from the shop with just about no coolant in it (I worry this could have caused an overheat situation leading to head gasket woes). From the paperwork the PO provided it seems like they replaced the radiator within the year of me buying it as well.

- I have owned this XC70 for about a year and a half now, and driven it around 15,000 miles. In this time I have seen the temp gauge go up twice: once while idling in the warm humid summer night for about 30 minutes, and once while testing the AWD in an empty, snowy lot. Neither time did it reach the red and I turned the engine off as soon as it started creeping up above the normal mark. Both times were low airflow situations so I have since replaced the radiator fan in the case that that is what was causing it issues. I have not experienced the temp creeping up since but I also am careful to not let it idle for long periods now.

- I pulled the spark plugs today and noticed a dusty green material on the ground strap of some cylinders. I am not well versed in reading plugs, but heard once that burning coolant can cause something similar.

I have run a sniffer test on the overflow tank and it passes every time (so it is not detecting exhaust gasses in the coolant system).
Attached are photos of the spark plugs, with the cylinder number in the top right corner.

So, what does everyone think? Also wondering what the chance of a cracked head or block would be in the case the HG is bad?

This Volvo has a fair bit of issues at this point, so I am weighting when and if I should go ahead and fit the head gasket if it is bad (the car is oil soaking the t-belt too I was going to go ahead and replace that, but if the HG is bad and I decide to replace it I will most likely wait till I pull the head to just replace the belt at the same time).

[volvolugnut]

The crusty coating looks suspicious, but I do not know the cause. The gap on all the plugs looks far too large. The proper gap is different to turbo and non turbos.
volvolugnut

[jonesg]

Go out when the engine is stone cold, don't start the engine, unscrew the coolant cap, is the tank pressurized?
does it hiss when opened cold.
Carefully examine the coolant bottle for any faint white chalky deposits.
If yes to those 2 tests I would get a bottle of block tester and see if the fluid changes from blue to yellow when idling.
That would be definitive to call the gasket.

If its limping along ok for now I'd be more concerned with the oil leaking on the belt, it could easily skip teeth.
Assess the coolant leak but attend the oil leak or you might be in for a $1000 rebuilt head too.
Most often its a cam seal. Not a huge repair but you're in Colorado? eesch thats gotta be cold..

[dikidera]

I have a question, jonesg. Why would the pressure overnight indicate a blown hg? I would imagine the leftover pressure would indicate that there is a seal.

[vtl]

Coolant leak into cylinder makes it more clean than the rest. Check with a flashlight or, better, borescope, if any cylinder is cleaner.

T2 engine uses MLS gasket (multi-layer steel). It never fails on its own. If the gasket is compromised it means there is a problem with the block and cylinder head. I would be looking at replacing the engine if gasket leak is confirmed.

Replacing the engine is also less labor intensive than doing the cylinder head. Because when you pull the head you are basically obliged to replace valve stem seals, clean and lap the valves, check valve lash, which of course will be bad and almost all tappets have to be replaced, and they are very expensive.

In fact, I would buy a donor engine with relatively low miles and in a relatively good shape, and rebuild it.

[jonesg]

I have a question, jonesg. Why would the pressure overnight indicate a blown hg? I would imagine the leftover pressure would indicate that there is a seal.

Hot coolant creates high pressure in the bottle, when the coolant goes cold there is no pressure in the bottle.
If you find high pressure and the coolant is cold then extra pressure came from the gasket.
Its remains under pressure because it was pressurized way beyond normal.
Sometimes the coolant will flow back into the cyl's and create steam clouds and misfires on startup.

[Griff]

The crusty coating looks suspicious, but I do not know the cause. The gap on all the plugs looks far too large. The proper gap is different to turbo and non turbos.
volvolugnut

Thanks for pointing this out! I just ordered a set of fresh plugs that I will gap correctly. It appears someone who has worked on this previously damaged the spark plug threads on two cylinders, so I am hoping the new plugs tighten correctly.

Go out when the engine is stone cold, don't start the engine, unscrew the coolant cap, is the tank pressurized?
does it hiss when opened cold.
Carefully examine the coolant bottle for any faint white chalky deposits.
If yes to those 2 tests I would get a bottle of block tester and see if the fluid changes from blue to yellow when idling.
That would be definitive to call the gasket.

If its limping along ok for now I'd be more concerned with the oil leaking on the belt, it could easily skip teeth.
Assess the coolant leak but attend the oil leak or you might be in for a $1000 rebuilt head too.
Most often its a cam seal. Not a huge repair but you're in Colorado? eesch thats gotta be cold..

Good to know! I haven't noticed it holding pressure in the past but I will check again for this. After reading you comment, I opted to replace the tbelt and cam seals yesterday so its still partially apart while I wait for a replacement lower coolant reservoir hose to come in. I will check for cold pressure and a chalky substance once it is up again. I have done a block tester, including the day I pulled plugs, and it always has passed.

Coolant leak into cylinder makes it more clean than the rest. Check with a flashlight or, better, borescope, if any cylinder is cleaner.

T2 engine uses MLS gasket (multi-layer steel). It never fails on its own. If the gasket is compromised it means there is a problem with the block and cylinder head. I would be looking at replacing the engine if gasket leak is confirmed.

Replacing the engine is also less labor intensive than doing the cylinder head. Because when you pull the head you are basically obliged to replace valve stem seals, clean and lap the valves, check valve lash, which of course will be bad and almost all tappets have to be replaced, and they are very expensive.

In fact, I would buy a donor engine with relatively low miles and in a relatively good shape, and rebuild it.

It appeared that the piston tops were all fairly carbon covered. I am replacing spark plugs within the week so I will take a closer look and compare them to one another. Good to know that there is fair chance of a crack if the head gasket failed, I will keep this in mind if I confirm it leaking.


Thanks for all the info, everyone! It is greatly appreciated. I will keep updates posted here.

[Griff]

Go out when the engine is stone cold, don't start the engine, unscrew the coolant cap, is the tank pressurized?
does it hiss when opened cold.
Carefully examine the coolant bottle for any faint white chalky deposits.
If yes to those 2 tests I would get a bottle of block tester and see if the fluid changes from blue to yellow when idling.
That would be definitive to call the gasket.

If its limping along ok for now I'd be more concerned with the oil leaking on the belt, it could easily skip teeth.
Assess the coolant leak but attend the oil leak or you might be in for a $1000 rebuilt head too.
Most often its a cam seal. Not a huge repair but you're in Colorado? eesch thats gotta be cold..

So I remembered to test this today finally. This particular Volvo does seem to have coolant pressure still when dead cold. I did not notice any chalky deposits in the reservoir.

However, this Volvo still passes the block test and my two other white block Volvos also seem to have coolant pressure on a dead cold engine (and those I am not concerned about head gasket integrity on).

What do you think?

[jonesg]

So I remembered to test this today finally. This particular Volvo does seem to have coolant pressure still when dead cold. I did not notice any chalky deposits in the reservoir.

However, this Volvo still passes the block test and my two other white block Volvos also seem to have coolant pressure on a dead cold engine (and those I am not concerned about head gasket integrity on).

What do you think?

I think you don't have a serious head gasket problem, maybe weeping hose clamp or whatever.
If the top hose is blowing up like a balloon change it.
Or swap it with one of the other volvo's and see if it reacts the same way.
If the hose has gone soft it can seep coolant at the clamps.

Try your block tester on the other volvo's.

[abscate]

I actually bought the car after the heater core blew (filled the cabin with steam, not just a failure where it trickles out like I have commonly seen associated with failed heater cores) on the previous owner while he was driving. He said he towed it to the shop, but drove it home 1.5 miles from the shop with just about no coolant in it (I worry this could have caused an overheat situation leading to head gasket woes). From the paperwork the PO provided it seems like they replaced the radiator within the year of me buying it as well.

That is a real expensive 1.5 mile - you get about 30 seconds once you run out of coolant before the head will warp. All fixable, but it needs a used engine or the gasket job