940 - Chasing Coolant Leaks

[2manyturbos]

If I was that far into, I would just keep on going. A 940 Turbo head gasket job is 6-7 hours total if you know what you are doing. Honestly, even if that doesn't turn out to be the problem it will be the best preventative maintenance you can do for peace of mind. The turbo cars are just waiting for the most inconvenient time to blow their head gasket at this point. Too many years, miles, heat cycles by now. Even a 1995 940 is 25 years old.

[iamrolling]

Mine lost coolant in a similar way when I had an exhaust to coolant leak.

I agree with 2manyturbos, though. Replace the head gasket. It's a good experience. The sealer in a bottle is for cars that you plan to push off a cliff after a few weeks.

[G-Tech 940]

Well, I certainly can't admit to knowing what I am doing, but I want to get it done, and most people seem to say it's pretty simple!

Thanks guys!

Edit: Well it turns out that the HG I had on the shelf is a Victor Reinz. Hopefully that's good enough to last me!

[iamrolling]

I'm going on 80,000 with my Reinz head gasket. Just make sure you clean the mating surfaces as good as you can. Keep going until there's no rust or dirt left, then keep going further until you stop seeing new rust on your rags entirely.

And if you have any doubts about anything you're doing, I'll try to answer any questions you have. Don't consider any question too stupid to ask, because this is one of those things where how close you get it to perfect will have a big impact on how long it lasts. And not all the data you need is immediately available.

[2manyturbos]

A Victor Reinz head gasket is fine. I've used them several times. Not on the same engine. They hold up fine. I think that is what is in my 940 Turbo, IIRC.

[G-Tech 940]

A blurry photo I took at the last minute, but I got the head ready for removal tomorrow. I will bring a straight edge to check the head, as one of the heater core hoses and one of the oil cooler hoses were aftermarket when I bought it, so potentially it has dumped its coolant at some point and overheated.

I will be replacing the cam, intermediate and crank seals, as well as the water pump, while the head is off.

I opted to swivel the exhaust manifold and turbo and downpipe, and just pull back the intake manifold. That should give me enough room to remove and replace the head.

[Mr. V]

Replace the timing belt and its tensioner while you are at it and be sure to adjust the valves.

Also the hoses and belts if at all dicey.

On the subject of head gaskets, is there any consensus about spraying on a product such as Copper Coat gasket compound on the bottom of the HG to help it to seal?

I've done the last two HG jobs using that and have had no issues.

[G-Tech 940]

Originally Posted by Mr. V

Replace the timing belt and its tensioner while you are at it and be sure to adjust the valves.

I'll have to look into adjusting the valves, I do have a bunch of shims on hand. Never done it before. This Headgasket job came about 3 months before I was mentally prepared to do it lol.

Some other parts I am replacing:

Cam gear for an STS adjustable
Cam Gear Pin for a solid stainless pin
Tensioner spring (OE) and roller (INA) although the INA roller on there was pretty good shape.
Timing Belt
Alternator Belt
P/S/Water Pump belt
AC belt is being left off for now.

[iamrolling]

Originally Posted by G-Tech 940

I'll have to look into adjusting the valves, I do have a bunch of shims on hand. Never done it before. This Headgasket job came about 3 months before I was mentally prepared to do it lol.

I wasn't prepared to replace my head gasket at all when my car started throwing the white smoke. I didn't think I could do the work myself, at all.
Think about replacing the nuts for the exhaust and intake manifold too. It will look really good when you put it all back together. You'll want to use locknuts for the exhaust.

Originally Posted by Mr. V

On the subject of head gaskets, is there any consensus about spraying on a product such as Copper Coat gasket compound on the bottom of the HG to help it to seal?

I was told to install my head gasket dry and not use sealant. I have seen it recommended before, but only for all aluminum engines.

[G-Tech 940]

Originally Posted by iamrolling

I wasn't prepared to replace my head gasket at all when my car started throwing the white smoke. I didn't think I could do the work myself, at all.
Think about replacing the nuts for the exhaust and intake manifold too. It will look really good when you put it all back together. You'll want to use locknuts for the exhaust.

Thanks! I am kinda just trying to keep moving forward with the steps until it's done!

I recently replaced all of the studs and nuts all the way around, intake and exhaust, they looked great! I used copper nuts on the exhaust manifold, and Volvo nuts everywhere else. After a few dozen heat cycles they don't look quite as nice, but they came off really easily (although a few backed the studs out, which I'm more than okay with compared with stubborn, broken studs! I use copper anti-seize and it seems to be working well.

[Mr. V]

Put some of that anti-seize on the spark plug threads to make them easier to remove as well as some dielectric grease on their tip and adjoining white ceramic area also.

[iamrolling]

I must warn you, NGK strongly recommends not using anti-seize on plugs with trivalent coating. Many plugs with silver-colored threads will have this trivalent coating. It can alter torque values in ways that can be destructive to the threads in the cylinder head. It's fine to use anti-seize if the threads have a black finish.

[G-Tech 940]

Head is off, and I scraped and scraped all of the gasket material off using a razorblade.

It feels smooth to the touch but doesn't look very clean, I went at it with some degreaser but it looks like there is oil baked into the surface or something. How clean is clean enough?

I also couldn't find any obvious sign of split HG....although there was definitely some bubbling/rust on parts of the gasket. Nothing was split that led to the outside of the head. I checked the head and block with a straight edge and it seems pretty bang on.

I installed the front cam seal, but poked it in a little past the chamfered edge. Will this be a problem? I had asked on the Turbobricks Discord and was told that it should be fine, and that some people even push it in a bit further if they have a worn camshaft.

I went to install the intermediate shaft seal, and tore it, even though I was using the Volvo special tool. I had to go back to Volvo to pick up a new seal. If I rip another I will be using the Reinz seal I have on hand. I was using Moly (LM 48) to lube it, the parts manager at Volvo suggested vaseline instead as it's less slippy.

Any tips on replacing the crank seal while the engine is in the car? I'm thinking it will be better approached from below.

[lummert]

After finding that you have already taken the head off did you check the heater hoses and pipes including the heater control valve for leaks?

[G-Tech 940]

Originally Posted by lummert

After finding that you have already taken the head off did you check the heater hoses and pipes including the heater control valve for leaks?

I did check and they were dry, but old, so I replaced the heater hoses as well as the heater valve. It was still dry before I started down this HG road.

The leak is coming from the exhaust side, I thought it might have been the coolant hard line or its heater hose connection above the bellhousing, but every time I felt it, it was always dry. The only place with a leak potential that is above the block heater is the HG as far as I can tell.

I can access the block heater a lot better now but still can't budge it from the hole. It's getting close to the point where I'm going to be forced to figure it out, because I'm on the verge of damaging it in the attempt to extract it. The tightening screw is loose and spinning, but the plug isn't budging from the hole yet.

[2manyturbos]

I always scrub the block surface with a piece of 3M red Scotch Brite and a little solvent by hand. Don't use those Roll Lock discs on an air tool. They can remove metal rather rapidly.

[Khrrck]

Originally Posted by G-Tech 940

I did check and they were dry, but old, so I replaced the heater hoses as well as the heater valve. It was still dry before I started down this HG road.

The leak is coming from the exhaust side, I thought it might have been the coolant hard line or its heater hose connection above the bellhousing, but every time I felt it, it was always dry. The only place with a leak potential that is above the block heater is the HG as far as I can tell.

There is also the O-ring at the water pump end of the hard pipe. When I replaced my pump (possibly OEM) I found that O-ring to basically have turned into a crumbly rock. Leaks can also run along the hardline and show up in weird places.

[G-Tech 940]

cleaned both surfaces with some brake cleaner sprayed onto a scotchbrite pad (cant buy red 3M unless I have a pro license or something)

Cleaned up pretty nice!

I installed the intermediate shaft seal again after messing up the first one.

I then used the special tool to install the crank seal. The outer lip of the innner ring was all messed up after I installed it but I was able to gently poke it in with a screwdriver. The inner lip of the inner ring should have been placed properly thanks to the tool. Fingers crossed there are no leaks.

Will be bolting the water pump to the block (without tightening it up) before replacing the HG and the head.

[2manyturbos]

Looks good. How straight is the head? Warp in both directions?

[G-Tech 940]

Originally Posted by 2manyturbos

Looks good. How straight is the head? Warp in both directions?

Thanks, I laid the straightest edge I could find across the head in all directions, and could only see the faintest sliver of a sliver of light, if anything at all. I did the same thing with the block, although it was a lot harder to check.

I was able to get the block heater to rotate in the hole with some hammer smacks, but have not been able to get it out yet. I would like to get that out before I put the head on, as the extra space gives more leverage. I sprayed a bit of PB around the edges to hopefully help.

[Khrrck]

Originally Posted by G-Tech 940

Thanks, I laid the straightest edge I could find across the head in all directions, and could only see the faintest sliver of a sliver of light, if anything at all. I did the same thing with the block, although it was a lot harder to check.

What's "the straightest edge you could find"? Metal ruler? Professional machinist's edge? Something in between, most likely?

As well as shining a light from behind, you can put the straightedge down on top of a feeler gauge and tug gently. Gauge pulls out with little or no friction = gap larger than the gauge.

[2manyturbos]

99.9% chance the block is perfectly straight. If you don't see any heavily corroded spots, it should be fine. If you don't have a machinist straight edge, just take your head to a shop and have it checked. Leave it with them to fly cut if is is more that .008" warped. I rarely see a redblock head that is straight unless it just came from the machine shop. Almost all of them are slightly warped.

[G-Tech 940]

Originally Posted by Khrrck

What's "the straightest edge you could find"? Metal ruler? Professional machinist's edge? Something in between, most likely?

Something in between, but I guess that's not the right way to do it.

Originally Posted by 2manyturbos

99.9% chance the block is perfectly straight. If you don't see any heavily corroded spots, it should be fine. If you don't have a machinist straight edge, just take your head to a shop and have it checked. Leave it with them to fly cut if is is more that .008" warped. I rarely see a redblock head that is straight unless it just came from the machine shop. Almost all of them are slightly warped.

I'm asking my local Volvo group for a recommendation on where to take the head. I have a guy who does machine work but I don't know if he has the equipment to resurface such a large surface.

Thanks!

[Khrrck]

Originally Posted by G-Tech 940

Something in between, but I guess that's not the right way to do it.

Well, depends on your risk tolerance and what you know about your straightedge. It's entirely possible that you have an edge that's straight within 0.001 but there's no good way to tell without checking against known quantities (another good edge, machinist's tools, etc). It's also possible that an only-sorta-flat head will work fine for many years. Given the hassle involved with the job it seems worth checking.

That said... if you want to DIY and have the tool on hand for future use, a decent hobbyist grade straightedge is <$30 on Amazon.

[c1800]

Scothbrite? no, no, no. The internet is littered with stories where scotchbrite was used. It contains aluminum oxide particles the spell death to an engine.