Needed to change the belt tensioner shock on my 95 E300D. While attempting to remove the TOP bolt, I totally striped the thread in the engine side into which the bolt fits. The hole is aluminium. The bolt is out, and its threads are OK, but if reinserted it now turns freely as it has noting to grab to. Not good.

I was thinking of helicoilig a new thread, and than getting a slightly larger diameter bolt, but a larger diameter bolt will not pass through the eye (bushing) of the belt tensioner shock.

I remember reading in this Forum about a year, ago a post from someone that had a similar problem. Now I can't find that thread.

How do I fix this thing?

Thanks

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

You probably can use a helicoil on the head which will give you the same size as you currently have. The helicoil tap is larger than the bolt size so that you can thread the helicoil into the head. You drill it out to the size specified, use the helicoil tap, insert the helicoil, bend the tab, and you are good to go.

If you do it right, you have steel on steel and you won't ever have a problem again.

Hi Brian, I am not equipped to do this myself, but will bring it to my Inde, on Monday. Are Indes typically equipped to do this type of repair? Would they have the necessary Helicoil parts, or would they need to special purchase it. Any idea what the labour time for this repair would be?


Thanks

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Hey Phil,

Any decent Indy will have a helicoil repair kit. However, a true M/B indy will have the metric helicoils in stock with the required tool to install them.

If they need to purchase the metric tools for that size, then the cost for the tools will be about $65.00 or so. But, if he has the tools for that size, it only takes five minutes to tap the hole and install the helicoil. It's a very fast process. The cost of the helicoil, itself, is less than a buck.

Unfortunately, you can bet he will charge one hour for it. If he wants more, or if he does not have the metric helicoil tools, I'm sure I can find the helicoil tools in McMaster-Carr that will allow you to do it yourself.

Thanks Brian, That's encouraging news.

My Indy specializes in Mercedes, so I am assuming that he will have a Metric version of the Helicoil.

I'll get him to put in my new Belt tensioner as well. I was going to do this myself, but I am not touching my car anymore for a while. Its seems that I have two left hands.

Thanks

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Don't get too hard on yourself, Phil.

Dealing with aluminum is always a PITA. It's very soft and, if the steel fastener doesn't want to release, the aluminum is going to give. Not much you could have done about it. Sometimes you can put some Kroil on it, or heat it, but, aluminum is always difficult when attempting to hold a decent torque.

It's a decent material to work with, but, never should have been used as a cylinder head in order to save 30 lbs.

After dealing with an York piston compressor (ie:vibration generator) AC bracket that was bolted to the aluminum intake manifold I invested in a range of metric helicoils. Worth every penny since stripped threads never occur at an good moment...

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Bill Reimels
Now down to one:
1972 300SE 3.5 W109 (Euro delivery)

I got some of my confidence back, and went to the driveway to try and deal with my stripped belt tensioner hole. I found a bolt that was the right diameter, but much longer than the original. Cut it to slightly longer than the original, hoping that it will reach deeper into threads that have not been stripped. It worked. It grabbed onto something, and now my old bolt tensioner is reattached. At least the car is now drivable again. There can't be that many threads holding it in place, so I hope that this whole Mickey mouse assembly does not come flying out, hits the radiator and causes much more expensive damage. Tomorrow I'll take it to my Indy, have him change the tensioner, and deal with the stripped hole properly. I'll get a new bolt as well.

Does about 5-6" of clearance between the Belt tensioner hole in the head, and the Radiator provide enough working space for my Indy to use the helicoil? What would a minimum working space clearance be?

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

If he doesn't, talk to a machine shop. They will most likely have a metric helicore and in many different sizes and thread pitches. Also, I would put anti-sieze on it since you don't want galvanic corrosion to take place again.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

That's likely not enough clearance. Remember, he has to drill the hole to the proper size and then tap it for the helicoil. The helicoil tools are at least 6 inches in length.

He will likely pull the radiator. So much for a one hour job.

Is there any other way of enlarging the hole in the 6" working clearance space? The material is Aluminium, so its soft. Will some-sort of small tool work?

Phil?

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'95 E300 Diesel, 264,000 Miles. [Sold it]

He could use a drill with a 90 degree right angle head. But, this is risky. Positioning it square with the hole is not the easiest thing to do. Might be possible if the hole is reasonably straight to start.

However, whether the Helicoil insertion tool will make it in a six inch space is questionable.

IF the hole is reasonable straight, which it should be he might be able to get away with it but I would doubt it anyways.

I thought the helicore was already half an inch which is screwed into the tool and the tool is about 4-5 inches long. Hard to say but he will have to make the call

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

Go to the McMaster Carr website and do a search on "helicoil". A page will come up that shows you everything you'd ever want to know about these little beasties, including the installation tools.

Your radiator (and fan shroud) pops out with four clips, four hoses and the two auto trans lines. Fifteen minutes to get it out the first time ever and ten to put it back. It probably takes longer to drain it than it does to remove it.

MB belt tensioners bite. My daughter's Ford Taurus's tensioner has a nice square hole to use a wrench handle in. None of this goofy wind up linkage and no shock absorber needed. Oh well. Plus, it's (MB's) buried under the water pump pulley and the power steering pump pulley. It was so much fun to replace when it quit.

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Norm in NJ
Next oil change at 230,000miles

Took the car to my Indy today. Instead of trying to tap a new hole, he used a slightly longer bolt. He must have grabbed some undamaged threads in the back, as he was able to torque it down. Its holding on tight,

The whole thing took about 1 Hr, including changing the shock tensioner. I think I was lucky this time.

Thanks for all the feedback,

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]