Helicoils

[daimlerdude]

Originally Posted by meltedpanda

I also have some not so good expereince with helicoils, but that is another discussion

I'd like to hear what your experiences were, and I'm sure others would to. So, here's a place to discuss them.

[Stretch]

They're not as strong as you might expect - things like time-sert are often a bit better. They are more expensive though...

[compu_85]

More expensive, but worth every penny

-J

[Strife]

Originally Posted by compu_85

More expensive, but worth every penny

-J

I agree here completely. When it absolutely has to work, spending less on less is absolutely foolish. The Time-Sert website does a good job explaining why.

I would say that in total, it took me at least 12 hours to do my 380 block (all 30+ holes!!!), and I can't see how a careful, experienced mechanic could do it in less than 6-8 hours, and I had the engine out.

I did do something possibly stupid - I wore the tap to the point where I barely finished the block, and the tools are not cheap and the tap is unique. I don't have the facilities to resharpen it. I used WD-40 as the cutting oil based on a website, and I now think that this was a bad idea, I should have used real cutting oil. OTOH, this IS high-silicon content aluminum and that tap and countersink tool wound up "cutting" a lot of glass.

[greazzer]

I fixed my A/C pump with helicolis. I agree there are better altenatives, but these held up fine and costs about $7 bucks for 5. See my Sleeper Part Deux thread as I have some pictures there.

[daimlerdude]

I just got what I consider the definitive word on whether 380sl head bolts can be re-torqued from my Indy Peter, a Stuttgard trained mechanic who's been working on MB's for over 30 years now.

According to him, the difference between the expansion and contraction co-efficients of the aluminum block and the steel blots can cause the bolts to loosen over time, which can result in a leaky head gasket.

However, the head bolts can be re-torqued by loosening them about 45 degrees, and re-torquing them to 60NM one at a time using the same sequence as MB specifies for inserting them. But this should be done only if the holes contain Helicoils and, preferably, Timeserts, which he put in my block. Whether re-torquing will cure the leak or not is hit or miss, but if it doesn't, the re-torquing will not exacerbate the leak.

So, I guess it is worth a try, after all. And, if I had known this before I developed a leak, I might have considered re-torquing my head bolts before a leak developed, as John Roncallo reported he did on his 560sl.

[JohnnyT]

Time Serts are the only way to go. You get what you pay for! While at it replace the stretch bolts. Pricey yes, but in the long run you are ahead of the game!

[letank]

Originally Posted by JohnnyT

Time Serts are the only way to go. You get what you pay for! While at it replace the stretch bolts. Pricey yes, but in the long run you are ahead of the game!

Timesert here as well, I did 3 out of 4 head bolt on the motorcycle and have used it for a whole season. This is an aluminum head as well.



I used the helicoils for the valve cover.

for the headgasket somebody has recommended blue devil headgasket sealant, lasted for over a year without issue... then the car was totaled... it is somewhere on this board... search user ah-kay.

[97 SL320]

Heli coils were invented in the 40's or so and the patent expired not so many years ago. They do work but you must be sure the end of the coil is one thread below the surface otherwise the coil will lift and jam the bolt thread. Also be sure the tang at the bottom is broken off and that end didn't come out of the thread. The original thread can start to crack and everything will pull out if the coil is barely below the surface so one thread below the surface is a must. When installing the bolts, be sure they start without cross threading as the sharp end can catch the bolt.

Time serts can't be used when you don't have enough material around the hole making heli coils the only option. The time serts ( or at least ones that look like them ) I've used accept a regular tapped hole a size or two larger. The hole must be drilled larger than you normally would use because the external threads on the time sert are pretty shallow.

Are you sure the tap was a special profile? The selling point of TS type inserts I've used is that standard taps can be used.

Tap Magic makes 2 kinds of tap fluids that work well.


" blue devil headgasket sealant, "

Yes, the stuff works, I've seen it used on a few cars with combustion to coolant leaks and the results are amazing. Basically the stuff is " Sodium Silicate" sometimes called "Water Glass (used to dip eggs) " and a few other chemicals , . The SS stays in suspension in water and does not fall out / clog small passages. What happens is that as the mix hits air the SS starts to solidify plugging the leak.

This this chemical had been sold by Moroso for years to racers with porous aluminum cylinder heads and crack repair equipment companies but, they would use it with the heads off.

[Stretch]

Originally Posted by 97 SL320

...

" blue devil headgasket sealant, "

Yes, the stuff works, I've seen it used on a few cars with combustion to coolant leaks and the results are amazing. Basically the stuff is " Sodium Silicate" sometimes called "Water Glass (used to dip eggs) " and a few other chemicals , . The SS stays in suspension in water and does not fall out / clog small passages. What happens is that as the mix hits air the SS starts to solidify plugging the leak.

This this chemical had been sold by Moroso for years to racers with porous aluminum cylinder heads and crack repair equipment companies but, they would use it with the heads off.

Is this stuff similar to the spray hylomar make?

[97 SL320]

Probably not, the Hylomar I'm familiar with is a blue non drying gasket shellac type compound you use directly on gaskets.

Hylomar was invented by Rolls Royce ( Pretty sure the aircraft engine division. ". . . . Pardon me, would you have any Hylomar? " . . ." But of course . . " " Hylomar, it even has wine. . " )

[Strife]

Originally Posted by 97 SL320

Are you sure the tap was a special profile? The selling point of TS type inserts I've used is that standard taps can be used.

I stand (sort of) corrected; the Time-sert tap is a standard, but hard to find S.T.I. (Standard Thread Insert) tap; also, it has a "class 3" characteristic, and, not being a machinist, I don't know the ramifications of this number. It is harder to find and more expensive than a typical tap of comparable size and character. After looking around, I will probably get another one from Timesert themselves.

I did make a stab at sharpening the one I have, using guidance I found on a machinist's website; under a powerful loupe, it seems improved, and it FEELS improved; we will see how that goes.

[Strife]

Originally Posted by 97 SL320

Basically the stuff is " Sodium Silicate" sometimes called "Water Glass (used to dip eggs) "...

I wouldn't use this on a BIG leak...because this is ALSO the chemical used to permanently destroy engines in the infamous "cars for clunkers" saga.

[97 SL320]

Originally Posted by Strife

I wouldn't use this on a BIG leak...because this is ALSO the chemical used to permanently destroy engines in the infamous "cars for clunkers" saga.

Using it in a coolant to oil leak would be a problem but thankfully they are rare.

My 70's International Harvester back hoe manual has a procedure to clean sodium silicate out of the oiling system ( when liner o rings leak ) .

I wonder if the cash clunkers engines were really damaged, the SS would tend to jam things up rapidly and might not have damaged the crank. X$#*^&#$!$#%##$# Liberals taking a good chunk of usable cars out of the mix and hurting low income people that survive on sub $ 2,000 cars. . .

[letank]

I must say that I have 2 timesert(s) head to toe...on the enclosed pict of the head bolt repair.

thanx for the SS infos.