I did something very unbelievably stupid, and I am hoping one of you or more could help me with advice!

I bought this cool little tool that was supposed to help lock the engine by stopping a piston through a sparkplug hole. I was using that so that I can unscrew the crank bolt off without the crankshaft moving.

Big mistake: The tool was not perpendicular to the cylinder wall, so when I was trying to unscrew the crank bolt, the piston pushed up and broke off the brass tip of the tool. I ended up having to remove the head so that I can remove the brass tip out of the cylinder! Talk about every mechanic's nightmare.

After taking off the brass tip, I noticed that the piston, after breaking off the brass tip, had continued moving up and pressed against the steel end of the tool. It resulted in a small, half-moon dent on the piston crown.

The half-circumference of the dent is slightly bigger than the eraser end of a pencil, and the depth at the curved notch is less than 1 mm.

Would this dent in any way affect the compression of the cylinder? Or what? I kept hearing advice to always be careful not to scratch the pistons. I need to know if the piston needs to be replaced or not. Nothing else in and around the cylinders has been touched or scratched.

Many many thanks in advance for your advice and help!

-DS

1993 Volvo Wagon 155k, 5 speed
1993 Volvo Sedan 95k
1989 Volvo Sedan 120k

Hey guys, many thanks for the reassuring advice! Nothing sharp or pointy from the ding on the piston (not extactly right on the crown but about an inch or so off center), but I will make sure to buff a little around the edges of the dent to be on the safe side. Will update how it goes after putting everything back together. Right now I am waiting for the head kit order to arrive from FCP Groton.

By the way, prior to the mess, I had been planning to replace the water pump, timing belt and all front oil seals. Sounded so simple back then, huh?

-DS

'93 240 Wagon, 155k
'93 240 Sedan, 95k
'89 240 Sedan, 120k

My favorite crankshaft counterhold "tool"...

Although I own both "official" counterhold tools for the B230 and B21/23, I no longer use either one. Instead, I prefer a piece of cotton clothesline (nylon or similar is OK too), for what is called "The Rope Trick". It's quicker and easier than the "tool", and the basic steps are simple:

1 - Pull plugs and rotate crank to #1 0° TDC Compression
2 - Verify #1 and #2 valves closed - look thru oil fill hole, #1 cam pointed slightly up and inboard, #2 pointed horizontally outboard.
3 - Rotate crank about 90° past TDC.
4 - Stuff about 3 feet of clothesline into # 1 plug hole, leaving 6" outside (feeding the rope in thru a short length of heater hose makes the job even quicker).
5 - Rotate the crank backwards until the packed rope stops further rotation.
6 - Use socket, breaker bar, and pipe extension to loosen pulley bolt.
7 - Tighten bolt the same way, but start with crank about 90° before #1 TDC Comp.
8 - When tight to spec, back the crank up a little a little and remove clothesline.

To my knowledge, this is the only "trick" holding tool alternative that allows tightening the bolt to book spec of 44 lb ft, then an additional 60° (B230), or 122 ft lbs. for B21/23.

Here's what some first-time users had to say:

• "The "rope trick" for holding the engine still while removing the harmonic balancer bolt worked like a charm. Honestly, I doubted that it would, but WOW!"

• "I finally had an opportunity today to use one of the "rope" tricks to help take off the crank bolt. All I can say is - it worked like a charm! Two seconds and I had the crank bolt off..."

* "I did this a few weeks ago exactly as ... described and it couldn't have been easier." 5/29/05

• "....the rope trick worked like a charm to loosen and tighten the crank pulley bolt!!," 12/28/05

• "tryed the . . . method without any luck but the rope trick worked fine to remove the pully bolt" 1-10-06

• "(thanks for the rope trick! Worked like a charm.)" 6-26-06

• "i just completed the task using the rope trick and my opinion is that it is extremely gentle as compared to jamming a screw driver anywhere. it required about 5 to 6 ft. of 1/4 inch rope and made mission impossible mission simple."

• 4-25-07 at http://www.brickboard.com/RWD/index.htm?id=1178645.

--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Yeah, I should have used the rope trick in the first place. Thanks, Lucid. I will remember that the next time I need to remove the harmonizer bolt.

-DS

So you want to spend another thousand dollars??

Clean up any sharp burrs and put it back togther!

The above advice cost you less than 2 cents but it's mine and I'm a-stickin' with it.
--
George Downs, Bartlesville, Heart of the USA!

"Would this dent in any way affect the compression of the cylinder?"

No. The loss of compression would be insignificant and immeasurable.

"I need to know if the piston needs to be replaced or not."

Don't think so. You have a .04 inch dent in the cast AL piston surface and probably did not affect anything.

I never heard of the tool you used. For cool tools, I use the 45 dollar crank holding tool. Others swear the rope trick is cool. They both work well.

Tom

A 1mm ding on the face of the slug AWAY from the ring edge should not be an issue, but if the half moon ding has a sharp edge, you will want to soften it via buffing to prevent detonation. That being said, if you had to use your entire body weight to break the bolt loose, you will want to remove the piston and check to make sure that the skirt hasn't been warped, especially if the "ding" is off center.

The only "tool" I have used for blocking a piston is grease soaked yarn fed down the spark plug hole, and lots of it.

jorrell
--
92 245 250K miles, IPD'd to the hilt, 06 XC70, 00 Eclipse custom Turbo setup...currently taking names and kicking reputations!