Hi,

I thought I was pretty clear to you how to get the bolt tight but I have a little extra time so I can tell you more about the reasoning I use to get to the approximate value they are calling for.

Yes that is the method I use on all my cars.
The bolt is the same in all the crankshafts even though the pulleys change from being a solid one to a split one with shims used to adjust the belt for the A/C. That's why you have six bolts.
Later the setup changed to a rubberized damper keyed to the belt sprocket only and a big washer to sandwich everything.
The torque values for either method works out to be the same to hold that belt sprocket in place.
Yes, its a lot of torque and is why you must get everything under it (belt guides) flat and straight or you can break the thin sprocket.

The method for turning, after preloading, works for most people who don't have a 3/4" drive, 150 Foot Pound torque wrench hanging on a wall because its too large to fit into a tool box.
I personally would not buy one unless I did rear end differential work.
I know this, because I inherited one from a close neighbor who passed several years ago. He used it for crushing a pinion nut washer on his Dodge truck. I don't think he ever used it again.

The impact driver works the best on the manual transmissions with the parking brake set or having the car on the ground and in gear.
Now that I have one car with an automatic, but have not needed to change a timing belt, as of yet.
That day will be as interesting as yours on the need to lock it that engine up.

You can reach that amount of torque with a half inch drive torque wrench. But it's not nice!
It's actually not very good for the torque wrench to use it at its extreme.
When it's used at the most upmost end of its range, it will not maintain its accuracy for being pushed to its limit.
A clicker wrench is more susceptible to stress because of the spring arrangement inside.
An old steel beam one can get bent and it still will work. All you is reset the needle arm back over the zero on the scale.
Trouble is but it's very hard to read the scale sideways when pulling hard with such a short length and the click is a nicer feature. I keep my beam one to check calibration of my clickers!

Torque wrenches are like pressure gauges and are meant to be installed where the gauge operates the majority of its time in the middle of its total range.
You would not install a 100 pound gauge to measure 15 psi or less system. If you wanted to read any small variances say around 10 psi it won't be as accurate as a 30 psi gauge.
The gauges themselves are calibrated to be "spot on" in their mid range to begin with.
The +/- tolerance accuracy is specified as its mid range of usage.
I use a 3/8" clicker to do spark plugs, drain plugs and so forth. This is because it fits in tighter places and their extensions and such are lighter.

I know if you read the Bently manual, they have a misprint of it saying 90 degrees, when it should say 60 degrees.
The hex head on the bolt has six flats. Divide 360 degrees that it takes to make a circle by six and you automatically get sixty degrees or rotation.
This make more sense if you think about it for mechanics to get the angle correctly without special tools!

In all cases of tightening, you are stretching an area of the body mass between threads and the top of the head. Preloading a certain amount stress is to remove looseness and provide tension or a starting point. The whole idea is tension against vibrational forces and rotational forces.
So on engines the idea of not using a torque wrench is ludicrous and so it is why, you have specifications written for specific areas.
On other things, like engine accessories, using brackets and alike you don't get anything specific but you learn quickly that too much or not enough can bring you grief!
You learn what "tight is" from experience!

Take a wheel nut for an example, that gets tightened to 80 foot pounds. That's a lot of torque in reality but who wants to have any to come loose?
How many of those get stripped or studs broken by the tire shops? That scares me somewhat, but apparently, that area is overly engineered to help get a better outcome, considering the motoring public options of servicing wheels and tires.
There are four nuts on light weight economy cars or five and up on heavier vehicles. Weight and larger diameters increase the forces the wheel can be subjected too! The more is better and at a point they get larger studs and nuts like on 18 wheelers.

The call out is of 122 for only one bolt and it can be done this way. First of all the bolt has a lot more bulk than the wheel studs do.
The diameter down there being held together is a lot smaller, it has nice snug fitting parts, if compared to a wheel rim and the joint is keyed to be driven by the key, so where can it go?
If you get it tight, as in even close, to the specifications called out, its not going to go anywhere.
Remember the 45 ft lbs. is a setting of preloading.
The engineering behind this is wanting almost three times that as a final torque value, of which I think, is a bit much for this joint. It is what it is though!

I'm not a rocket scientist, so I try to live within my means and/or tools and justly getting it close with the use of a tool that I know can tighten stuff up really tightly.
A half-inch impact and a half-inch torque wrench are made to be rather equal in their capabilities of work assigned for them to perform.

Do the best you can, it will come out all right!
As my point being is that somethings are just overly engineered, for safety to cover their buns, over the actual purpose.
This is only a good thing considering the general public and the way it is today!

Phil

Dave, I had that setup on my 80 244. I still have the mount and the old fan/clutch around somewhere. When that clutch failed, I replaced it with a FlexFan with a custom aluminum spacer that IPD was selling a the time. That set up is way lighter that the Clutched fan. That was IPD's selling point, lighter less stress on the WP bearings.

Happy New Year.

Yep, a large nut at the center that secures the unified fan / clutch assembly to the fan side of the flange that is secured to the water pump flange hidden under the water pump pulley bell.

In that instance you would use a chain or strap or other type water pump wrench around the water pump pulley bell. (As you would if doing this in your 1988 and the four 10mm hex hardware to separate the fan and clutch from the 1988 240 wasserpumpen, though much less force required of course on them four small sets of securing hardware.)



There exist a host of chain wrenches and other tools members here on this forum use. I mention a chain wrench as it works for me as counter hold. Other members will offer better suggestions, I hope.

I also had this same water pump fan on two 1979 240s (242 GT and 245 DL mustard or autumn colored yellow wagon).

You remove the two securing self-tapping metal screws that secure the water pump fan shroud to the radiator. You have to choreograph the left arm handling the (clockwise) counter hold on the water pump pulley bell and the other right arm to remove the center nut using a hex socket and ratchet or wrench (hex end). I found the center nut to be under some torque. A steady hand on the counter hold as you use a steady hand to remove the center nut.

One the nut is loose, you hold the weight of the fan / clutch assembly and unscrew the center nut.

With fan removed, you can remove the fan shroud.

It is a paradox as you can't remove the fan shroud without the water pump fan removed. You can't remove the water pump fan without removing the two top fan shroud screws and working around a loose fan shroud without marring the engine side of the radiator.

As Dave Volvo From Heck mentions, for more clearance, and avoid damaging the radiator, to drain the coolant and remove the radiator after freed shroud yet before removing the single fan / clutch assembly.

You repeat the exercise for four sets of 10mm.

You can upload any size image to BrickPix gallery so long as the image is under 1,024 kilobytes in file length, or 1 megabyte. Jarrod has not revised the BrickPix instructions yet. Tho your image is fine!


The 700-900 FAQ instructions for water pump change, the link is in a prior post in your thread mention inspection and test for resistance when pushing the fan blades when cold and with a hot radiator of the water pump fan viscous clutch. A nearly 40 year clutch may be worth of inspection or replacement.

You can install the same fan assembly as you have on your 1988 (or up to 1995 940) if you have a spare. Though inspect the junkyard pull or used for oil leaks or lack of resistance (fan spinning freely cold yet more so warm means failed).

When driving during warmer weather, as the engine heats to normal temp, you should hear the water pump fan roar under the hood. Though you won't usually here in in cold weather.
--
Give your brickboard.com a big thumbs up! Way up! - Roger Ebert.

Hey Phil,

Normally, I don't post when I haven't a clue what's going on, but today I'm not feeling normal. This "central bolt" is in a fan clutch according to the original post in this thread. Have we moved on, to the crankshaft in this thread?

Reason I ask, is I know of very few left-hand threads in my Volvo experience, but one of them is a central bolt on a cooling fan, and I've never seen the fan clutch someone posted earlier belonging to a 1980 240. I've owned a '79 for nearly 20 years as second owner -- it has the same fan and clutch provided on all the 80's and 90's 240s where there's room to sneak in a 10mm wrench to remove four nuts.

The left-hand thread I'm thinking of is not something anyone would hang a breaker bar on. It attaches a plastic fan blade to an electric motor.



I think you have one of these in your '92 if I'm not mistaken. I know this isn't the fan the OP is fighting, but the principle might apply, given the fan in his picture is outside of my experience.

But as abnormal as I feel today, I'm reminded no one would use a rope trick to remove a fan bolt on a water pump, right?
--
Art Benstein near Baltimore

Sometimes I wake up grumpy; other times I let her sleep.