Well after measuring my pistons agian and comparing them to specs from the disc something isnt adding up. The turbo motor I took apart started fine in cold weather, had a good compression but spun a connecting rod bearing. When I measured the piston it was over 20thousands off the spec. However if it was that much off logic tells me that the piston should slappin around, have bad compression and marks all over the pistons and sleeves off slapping around,but there isnt. You can still see the machine marks from the factory. The same problem goes for the non turbo engine took apart. The pistons measure far off the spec yet there is no evidence of piston slap on the parts anywhere.

90.89 mm is 3.58" yet the piston I measured was 3.55". And yes I know how to use an outside micrometer. What are the real specs??

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Is it tapered or out of round?

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

they are a little of both

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Are you sure you are measuring in the right place? Pistons are often larger in one direction than the other (parallel to the pin vs. perpendicular, I don't remember which is usually larger.) Measuring the skirt or the lands? Have you checked the calibration of the micrometer?

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1987 W201 190D

ive measured them in different places at the lands at got no measurements close to the specs. I measured like you do the sleeves diagionally directly across on the top. I did check my micrometer to see if it was calibrated right and it is.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

I am not sure what vehicle you are working on.

__________________
84 300D, 82 Volvo 244Gl Diesel

2 engines that are aprt. a non turbo from an 81 300D that had a bad body and the po didnt change the oil much so it had to get changed with a junkyard one. The other is a turbo motor from an 83 300D that spun a connecting rod bearing. But I know one thing with the numbers im getting the evidence from being worn almost 30thousandths isnt being shown in ether of them at the the sleeves, pistons. I can still see the machine marks and no evidvence of piston slap whatso ever which 30thousandths of wear should do and thats why I questioning the specs in the FSM. The fsm has been wrong before in the past. It would be nice if someone who has the orginal hardcopies and looked up the specs.

Can someone whos rebuilt a 617.912 or a 617.952 engine please chime in.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Fit the piston in the bore, push it over to one side, and total clearance is whatever size feeler will fit between the cylinder and piston.

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

il try that and measure them at the skirt and see what I get. The bently book for mk3 vws shows you to measure the pistons at the skirts not the top so ill see what I get.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Not pointing fingers, but raising the possibility- w/ 2 engines open, is piston confusion a possibility?

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

no since the design of the non turbo and trubo pistons are different. I labeled them all and put them in seperate containers. Fastlane doesnt carry the right pistons for the non turbo.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Is this the #1 piston?

Measure another piston. twalgamuth wrote about the #1 piston being a different size.

__________________

after measuring each set of pistons at the skirts they were in spec. However I brought out the haynes to use a refernce who got their specs from mercedes. However its quit clear that the authors of haynes cant do basic math.

90.885x.03937=3.5781
90.89x.03937=3.5783
90.90x.03937=3.5787
90.86x.03937=3.5771
90.87x.03937=3.5775
90.86x.03937=3.5773
90.875x.03937=3.5777

haynes has this:
non turbo:
piston1=90.89mm(group 1 piston)=3.5811
pistons 2-4=90.89mm(group 1)=3.5811
piston 5=group 2, 90.90mm=3.58115
Turbo:
group1-90.885-90.865mm(3.5787-3.5801")
group2-90.865-90.875mm(3.5801-3.5805"

I dont have to buy pistons!

The haynes authors should visit this website:
http://vulcan.wr.usgs.gov/Miscellaneous/ConversionTables/conversion_table.html

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)