I first noticed the coolant tank cracked on top. After it's replaced, now coolant is splashing under the hood and I can't find exactly where. I did a block test and find trace amount of exhaust gas in coolant (color changes but not very fast). So there could be block leaking.

So my question is: is it possible to fix this kind of small leak by retightening all the head bolts (12 or them)? If so, how difficult it is to remove the valve cover to reach these bolts? Will it help if I overtighten those by say 20%?

Also how effective are those head gasket sealers? Can I temporally fix this by adding some of those?

Thanks!

I have a 2010 C70, by the way.

 

More than likely the engine has been overheated at some point. Your tune up in a can, no sorry head gasket in a can - might give you hope. But you will need to solve the problem with some real work. You can always try the can of hope -

The head bolts are torque to yield bolts. They are stretched when installed and should not be reused. It's amazing if you measure a used one against a new one - But you could try tightening, (if they don't break) after removing the cam belt, top cover, tightening, cleaning all the goo off and rolling new goo on, setting the cams back up, reinstalling the cover and belt(s).

Let us know how that works out. I'm always up for a positive outcome to a potentially expensive problem. Sorry for your problems, have fixed many of those - It is disappointing that your car (and many other Volvos in that series) do not have a low coolant warning system.

 

I think you are right, overheating caused the problem.

Is there any difference between head sealers? Any brand recommendation? I only want to do a temporary fix to pass this "chip shortage" before I can buy a new car!

 

960 volvos with the 6 cyl version of your engine - the head gasket would leak coolant externally in the right rear corner of the head, down the side of the block. Rather than replace the head gasket on an old Volvo - I would offer and use if approved by the customer - "kseal". Head gasket in a can. It would solve the external leak on the 960 engine in the right rear corner. Customer was happy, not much money spent on their old car.

A customer asked me to try it on their "slightly" damaged head gasket - I would not recommend it for that purpose.

If you do try it, drain some/most of the coolant out, remove the thermostat and pour the kseal directly into the cylinder head - if you just put it in the coolant bottle very little kseal will ever get to where you want it. That may be difficult with the new style thermostats that have no gaskets - never tried it with those.

 

Actually, that's the exact brand (K seal) I just bought before I read your posting...
Remove thermostat is a good suggestion (if I can find it). I will flush the radiator before I pour this in.
Thanks!

 

I just found a big leak on the upper hose: the small hose almost completely disconnected from the T:

Why do they make a hose like this? They don't know thermal stress will eventually cause separation of two different materials? This is worse than simply drill a hole on the bigger hose and use a metal bracket to press the small hose onto it.

 

After I fixed this hose, now I found three more coolant leaking at three locations:


Since these are on the transmission side, I guess the head gasket on the transmission side got blown? This may make sense since the temperature could be the highest in there.

If this is the case, I don't think the sealer will work. Right?

 

I have to say my dad tries that sort of thing a lot (I mean over 60 years), so I don't have to. It does work somewhat. I have no idea what it's like afterward if it doesn't. I would certainly be concerned about plugging the heater, but of course on Volvos that's not very devastating. The leak to the outside is pretty easy to seal, and I think that's likely to work. The leak to inside the cylinder is the real problem. I know over the years he's used Bars Leaks and K&W. I notice online Blue Devil is another one that gets good reviews but I don't think I've ever heard of that one.

 

Before I donate this car, anybody knows how many hours it may take to replace its head gasket (without any other complication) on average? I did one on a Honda before, but never tried this one.

 

2 days work. That's after you have done a few, and have the special tools and instructions you will need.

 

2 days to make $2700, sounds pretty good if I have the time...

 

If you have a damaged head gasket due to overheating - the head will be warped. You cannot just resurface the head because it's warped on the top as well as the bottom. The head must be straightened or the cams have to bend as they turn. A valve job is needed after that on a straightened head. That process takes a minimum of a few days.

Once you get the head back use new head bolts - If you've never done a head like this - there are plenty of chances to screw up putting it back together. Exhaust studs break, turbo has oil leaks afterward, you can't get the bolts in the water pipe on the side of the head and end up stripping them.

Solve your leakage problems first - those drops on the block are not coming from an externally leaking head gasket.

 

I will check the transmission fluid first: if it looks normal, you are right, the water didn't come out of the transmission...