I'm checking my OM602 head bolts for stretch to see if I can reuse them. I assume I should be measuring only the shaft itself (MINUS the head), no? Otherwise, mine are all WAY out of spec! I have the specs from the manual, but nothing assuring me that I'm measuring in the right places.

Thanks, all!

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

Checked my computer version of the FSM: hold a straight edge against the threads, they all should touch, if some don't, they have been stretched, replace the bolts. I'd have to re-read it, but I think you are supposed to replace in sets.

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1984 300 D runs, interior
1984 300 D light hit in front, RUST, mint/perfect dash, decent interior (see above), parts car
(hate to kill one)
1998 Dodge diesel

Thank you, sir! I just found a section in the FSM that covers proper measuring technique, and mine are all in spec.. good to go!

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I believe my favorite machinist measures in the necked area. The diameter there. It is a go no go situation. Each time they are stretched it gets narrower until it is too thin to use.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

IMHO this isn't worth messing around with. Every time I've re-used stretch bolts it's not gone well. My time is valuable so to me it costs less just to replace them every time then not worry...

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

What's been the problem with reusing head bolts? Why would the FSM advise checking them for stretch if they shouldn't ever be reused? If they're in spec, and clean, and you chase the threads in the block with a tap first, what would the problem be? I'm not asking to be argumentative, but rather to learn about the matter.

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

Tell me more, Tom. The FSM illustrates the measurement as the shank -- the length from the bottom of the head (or the seating surface) to the tip of the threaded ends. Mine are all very close to spec in that regard. Thanks!

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

Apparently there is more than one way to measure a stretch bolt. He measures the diameter of the necked down area in the center, but that is what the fsm showed for that bolt.

To the fellow who's time is too valuable to measure mercedes diesel head bolts I would ask have you ever bought a complete set? They don't cost what a chebby bolt costs and they are made out of some serious steel.

IIRC they are nearly $20 a peace. I am not missing any meals but I surely would not buy a new set just because I had a bad experience with some other brand of bolts.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Thanks, Tom. I think the head bolt are down to 2 or 3 bucks apiece now, so I can see why someone would just replace them all, but if you have the means to measure them accurately, and they are all in spec according to the FSM, I don't see the issue with reusing. Why toss perfectly good bolts? If someone's got a compelling reason not to reuse them, I'm all ears, though.

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

When I did my 603 (14 head), I checked around and discovered that MB had gone through three revisions of bolts. The aftermarket ones (local shop I use frequently) were not the new super-dupers. I used the MB supers. Check EPC to see what's "new" for your engine, then check to see who's selling what.

To my mind I can't imagine spending a day of labor and $100 on gaskets and save $70 on bolts (for my six; YMMV on labor, bolt qty and $).

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James Marriott
2003 Buick Regal
1983 300D (228k, frau Auto)
1996 Suburban K2500 (192k, 6.5 turbo diesel/4WD towmaster 10,000)
www.engineeringworks.biz
1987 300SDL junker 170k
1982 300SD junker, 265k

If they meet mb specs they are good enough for me. I'll spend my $70 on something else.

But you are free to replace them if you want.

I just looked at fastlane. I thought they were a lot more expensive than that. Have they gone down?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.