I am about to tackle a cylinder head removal/resurfacing/gasket replacement tomorrow. I am worried about the Exhaust Manifold Bolts. How effective is a Battery-powered Electric Impact Wrench on those bolts? (cost: $39) Is it worth the time? The nuts/bots look good and rusted-on! Do you guys think am impact wrench will strip/break those bolts? Or should I just rely on PBlaster and a long 1/2-inch good breaker bar?

[[ southern fried volvo ]]

I speak from experience with electric powered impact wrenches. I used to use 110 volt Dewalts and the like for anchoring bolts and welding studs into a concrete bridge before we welded rail supports on. (professional go kart track) Expect to pay a couple hundred dollars or so for a decent electric impact wrench (further money is required when you have to get the clutches replaced after ### hours of use).

About a year ago, I assisted changing a tire on someone's Chevy van. I used the lug wrench supplied with the vehicle, the owner used a cheap "cigarette-lighter-impact-wrench." They set to work with the impact wrench on one bolt, and I worked on the others with lug wrench. I had five bolts off and the replacement tire ready to go before the impact wrench could even budge the other nut. It also did not seem to supply a lot of force. The way it worked was to spin a weighted clutch wheel and then once the proper RPMs were reached, it would quickly engage the drive. This served only to shake the operators hand a bit and did not loosen the lug nut.

I had to replaced the exhaust manifold on my '86 Pontiac a year ago and I was able to do it with a standard Craftsman 3/8" drive and no bolt loosener. Looking back on it now, PB Blaster would have been a good idea. -not for the sake of easier removal, but for the sake of not stripping or shearing a bolt.

Regarding the life expectancy of Thermostats. Some auto manufacturers design their thermostats to last a LONG time (+100,000 miles). -and other expect you to change it ever time you change the coolant. My Pontiac uses a cheaper style of thermostat and it's only a $9 part. My friend's Nissan Maxima has a good high quality thermostat ($39) and we just changed out the original at 130,000 miles. This is a bit long however, and even so I would have changed it at the 2nd coolant change.

How a thermostat works: There is a wax pellet inside the housing that changes size (dramatically) when the temperature changes. Think of it this way, the thermostat stays closed until about 195 degrees and is fully open by 220. In a 25 degree spread it has moved a piston about 3/4" of an inch. Depending on how well the piston is sealed, the wax can leak out slowly over time. When it fails, it will fail in one of 3 positions: fully open, paritally open, or completely closed. I'm sorry that yours failed in the closed position (my Mom's Oldsmobile Sillouette did this back in 1994). In the winter of 1996, my Pontiac's thermostat failed in the open position, -and thus the car could not warm up. Medium-warm to cold air was all that the heating vents could produce and the engine was burning more gas than it should (running in 'cold' warmup mode). A coolant flush and a thermostat later, the car was running great.

As far as Volvo thermostats go (and most Import vehicles in general), I would assume that the official Volvo part would be of higher than average quality and you would be safe to go 2 coolant changes before replacing (no longer than 5 or 6 years). Any domestic car, -I'd change it every coolant change (2.5 to 3 years).

Good luck with your engine work and God bless,
Fitz Fitzgerald.
--
'87 Blue 245, NA 214K

YOu definitely DON'T want to use the impact tool on the exhaust manifold bolts.
You need to precisely control the torque and honestly they aren't on there that tight. They probably are rusted, but you may do fine with simply wrenching them off. PB Blaster is your friend and there's no such thing as "too much". :)

Now, if you do get a LOT of resistance from them, or you find that they're pretty rusted, you have to stop and take a different tack. You'll be putting new nuts on anyway, (RIGHT?!!) so you take a small sharp chisel and split the existing nuts. You don't need to go clean through them, and you don't want to damage the studs. Just a little split will release them from the stud just fine. Then it will be removable with a wrench or by hand.

Good luck! You've got your work cut out for you but it's something you can do with success.
--
Rob Bareiss, New London CT ::: '86 244DL- 215K, 87 244DL- 230K, 88 744GLE- 198K, 91 244 180K

Save your money on the battery powered impact the one that uses the car battery or cigar lighter. Me and my coworkers found they last about 4 tires before they burn out. A breaker bar or cheater bar will work just fine.

I wouldn't use power tools for either removal. I do have a DeWalt electric a/c
powered impact driver. The thing is fantastic but I'd be afraid of damaging
something important with that removing headbolts or exhaust manifold bolts.
Just use lots of pb blaster like the other post says. I replaced my head gasket late last year and I used a long breaker bar, 14mm 6 point impact socket (head bolt size) and I added a pipe to give more leverage for the really tough head bolts. You do need a really strong socket for the head bolts. Wish you well.

Dave 82 242ti

On bolts and nuts exposed to exhaust gas temps, I'd agree with Steve and put a greater emphasis on soaking them with a quality product like PB blaster or such. Heating the nuts and bolts up before applying the penetrating oil will cause a capilary action that tends to draw the fluid into the threads and breaks the corrosive bond. May take more than once.

Impact guns are nice, but in some cases to much torque will cause greater problems. Either way, do use the penetrant to break the bond.

Don't waste the $39.

You can easily break manifold studs with a short box end wrench....use PB Blaster and prayer of Jabez.

The head bolts will be the tight ones....use a REAL air impact wrench or a breaker bar and a long ass pipe extension.

Either way a battery powered impact wrench, expecially a $39 one, would be pointless.
--
www.fidalgo.net/~brook4

Thanks for the advise... but now I am REALLY worried! I haven't been able to heat up the engine and/or spray PBlaster on the exaust manifold bolts beforehand.

The engine overheated over the weekend, ruptured the cylinder head gasket, and I will have Wednesday and Thursday to get it fixed. However, I still would rather attempt it myself than get burned (again)by one of the local auto shops!

Amazing: A $10 thermostat failure leads to a $600 major engine repair. Let's here it for Preventive Maintenance!!!

[[ southern fried volvo ]]

I've never used those. Whatever you do, soak those suckers in PBlaster for days ahead of time. You might try heating them up and applying the Blaster while hot and then cooling down.