Well, thanks to an improperly calibrated (read "cheap") clicker torque wrench that overtorques nearly 10 ft/lbs above what it's set for, I now have cracks in 5 of the 6 runners on the intake manifold for my '87 300D.

After having the intake off for cleaning and other maintenance, I reinstalled and torqued it with said torque wrench, test run the engine until it was up to temp for about 15 minutes, then shut it down and started checking things out a few minutes later.

The cracks are on runners 1 thru 4 and 6, just on the front side of the runners, above the upper mounting bolts. You could see after running the engine where the gasket "hook" that locates on the upper bolt had been crushed and mashed out.

I checked the clicker against my old balance beam torque wrench, and found that the bloody thing way overtorques when set for anything over 5 to 10 ft/lbs. What should have been 18 ft/lbs (25 nm) for the manifold bolts was probably 30 ft/lbs or better, the way the gasket ended up bowed between the runners.

Located a used intake manifold and it's already on the way, along with new gaskets. Clicker torque wrench is somewhere about 100 ft down inside a patch of woods (I threw that bloody thing as far as I could, I was PISSED!), replaced with a smaller version of my old balance beam from Sears.

Question is, would it be worth taking this manifold to a competent mechanic/welder to see if it's repairable? Cracks appear only to be in the 12 to 9 o'clock positions on all affected runners.

Second question, with putting on a different manifold, is there anything that will have to be adjusted/recalibrated, such as the throttle linkage?

Third, new small balance torque wrench has Nm scale, calibrated in 5 nm increments. Would you recommend still sticking with 25 nm torque, or something far less? I don't want to repeat this experience.

Check with a local machinest,they can probably weld your damaged intake.
Stick with the M.B. specifications for torque.

Man, I'm about to put mine back on! And I don't have my own torque wrench. This scared me. Is there a specific tightening pattern for the intake bolts?

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1987 300D wvo on the way!

I just tightened them to snug...

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

POR 15 makes a manifold repair kit. I have had good luck with their products.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

Hmmm, I think I've seen some of their products advertised in an Eastwood catalog, same guys? I'll see if I can find them doing a Google search.

Hooray, just answered the door, new gaskets just arrived from buymbparts, not bad only 2 days since I ordered them. UPS e-mail last night said used manifold should get here Thursday.

Believe I'll take the cracked manifold to a local machinist. With only 15 psi boost at most, I'm not really concerned about making the cracks pressure tight - where they are, I'm concerned about making sure that the gasket seating surface is still flat and true, and mechanical strength since they're right at the primary attachment point to the engine.

Also ordered a couple of 6 mm hex head 1/4 drive sockets from wihatools.com. Found out the hard way that it's a PITA trying to use 3/8 drive on those lower bolts. That may have contributed to the overtorquing too, so I'm eliminating that problem as well.

As far as the crossover pipe - I believe I understand now why the previous owner left that small L-shaped bracket between the crossover pipe and the EGR/mixer housing disconnected - to allow for some movement/thermal expansion of the crossover pipe and manifold and help prevent what just happened to me (crushed gasket and cracked manifold). If that's the case, no problem, that bracket will spend the rest of it's days stored in the trunk.

Do the two bolts at the crossover pipe/manifold connection have the same torque spec as the manifold bolts (25 nm) or just tighten till snug? 18 ft/lbs seemed excessive for these small bolts, I left them at 10 ft/lbs.

[QUOTE=retmil46;1246649]..................................... Clicker torque wrench is somewhere about 100 ft down inside a patch of woods (I threw that bloody thing as far as I could, I was PISSED!), ............... QUOTE]

Yes! I can relate. There isn't a patch of woods near me.(Maybe I can send you my "Harbor Freight Special" and you could "place" them in a side-by-side grave.)

Fortunately, mine just snapped off an oil pan bolt which I still have not been able to remove successfully.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Hmm I have a Utica click-type that works quite well

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)

Comparing one uncalibrated torque wrench to another uncalibrated torque wrench COULD mean the correctly calibrated wrench is rusting in the woods.

Considering the shape my intake manifold is in right now, I'd be willing to bet otherwise!

FYI, there's a used one on eBay here:

http://cgi.ebay.com/ebaymotors/Mercedes-Benz-MB-Diesel-Intake-Manifold_W0QQitemZ130017504360QQihZ003QQcategoryZ38634QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

No affiliation with the seller, etc etc...

Guys, thanks for all the offers on helping find a replacement manifold. I'd already located one last Saturday and it should be here tomorrow. However, if when it gets here, it turns out to be a beaten up POS, I may end up taking advantage of one of these offers/leads.

For initial install of the replacement manifold, considering that it's basically a plastic gasket, I believe I'll go with "snug" and use the small balance beam to verify just how much "snug" is. After an initial run and cooldown, then go back and verify that they're still "snug". Same with the two bolts on the crossover pipe, and leave off the bolt on the mixer housing.

"Considering the shape my intake manifold is in right now, I'd be willing to bet otherwise!"

Not to beat a dead horse but it's never good to automatically associate a result with a previous action. It doesn't always follow. You probably had vegetables earlier in the day but that doesn't necessarily mean that's what caused the cracks.

Hey, I know where you're coming from, I was just being flippant earlier.

The balance beam is a 1/2 drive Sears Craftsman, and it has been calibrated before, been stored so it didn't get beaten and banged around. Reason I didn't use it to begin with is that it was overkill for the task at hand, and only had graduations every 10 nm. In hindsight, I should have checked the clicker against the balance beam BEFORE I used it.

I'm looking at other possibilities besides the torque wrench that may have contributed to the problem, and taking actions to remedy these as well. But the gasket being literally crushed and squeezed out from underneath the upper mounting bolts, and visibly bowed up between the runners, does point to overtorque as the main culprit.

On the bright side, the replacement manifold arrived this morning (Wednesday), and is taking a nice long overnight bath in 3 gallons of B20 to clean out all the crud inside. An added goodie was that the brackets for fuel lines 4 thru 6 that were missing on mine were still attached, along with the plastic bracket for the throttle linkage on runner #5, and the ALDA sensing line fitting was still installed as well. Manifold itself was in good shape as well, all gasket surfaces checked out, no cracks gouges or dents. Not bad, $75 for a good manifold and got some spare parts to boot.

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Just say "NO" to Ethanol - Drive Diesel

Mitchell Oates
Mooresville, NC
'87 300D 212K miles
'87 300D 151K miles - R.I.P. 12/08
'05 Jeep Liberty CRD 67K miles
Grumpy Old Diesel Owners Club

I would hunt around for a used manifold first....the bolts for it are also threaded into alloy ( head.) with a new set of intake gaskets you only need to snugg them up....your not holding the car together with them !

I would say that even tig welding it will be pricey and then it needs surfacing too. Yep....find a used intake.

BTW......
I never use a torque wrench for the manifolds/brackets/glow plugs/etc.
I have over 40 years developed a feeling for the smaller fasteners that lets me do my job without cracking manifold ears off.

The torque wrench idea is okay for head bolts/flywheel etc and I use one on those.

The factory setting for those small bolts though is low and even a few percent out will strip the threads or crack the part. When they assembled it new everything was clean and equal.

You can feel a thread begining to strip or a part not seating quiet right without a torque wrench.

I use a Snap-On short handle flex head 3/8th drive ratchet to assemble most eveything.
I have broken stuff in the past but not due to my wrist action.

You develop a feel for this after a while.

OAAT....Isn't that 1987, a 300SDL ?

.

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"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."