Heli Coil for 1992 Deville 4.9

beveluv · #1 (**permalink**) 10-16-09, 03:48 PM

Has anyone used heli coils on a 4.9L engine and if so, where did they obtain the Heli Coil install kit? I have a 1992 Cadillac Deville 4.9 V8 and just 1 of my bolt holes was stripped of its threads when I was replacing the head gaskets myself. I would prefer not to have to spend the $500+ for a time sert kit that I will only use once if its not necessary. Does anyone know someone who does the insert in the Orlando, FL area? Its my understanding that I only get 1 shot at installing the Heli coil correctly (has to be perfectly straight which means I might be forced to remove the block from the car) and I don’t want to destroy my block.

Thanks!

**Ranger** · #2 (**permalink**) 10-16-09, 05:07 PM

I would not chance using a Helicoil on a head bolt hole. I don't think it will take the torque. You do get a second chance. Timesert makes a big sert (over sized timesert).

drewsdeville · #3 (**permalink**) 10-17-09, 12:05 AM

YES.

I purchased my first caddy with leaking headgaskets for cheap. You know what it was? A '92 Sedan Deville.

All was fine during the replacement until the final torquing step, the 6 90ft/lbs bolts. Most of the pulled the threads. I helicoiled only the 6 holes, block in the car. Worked great. Car ran like a dream until it was rearended by a fullsized E350 Ford van.

90ft/lbs on bolts as large as the 4.x headbolts (M12 x 1.75)are just fine for helicoils. the helicoil effectively transfers the net torque to more threaded surface area to grip If a helicoil won't hold it, the original threads would have pulled at the factory.

If you want to use timeserts for peace of mind, be my guest. However keep in mind that helcoils have been an accepted method of repairing head bolt holes for decades and are much cheaper in price.

You can pick up a M12 x 1.75 helicoil kit at napa for somewhere around $100

beveluv · #4 (**permalink**) 10-17-09, 02:36 AM

Thanks for the info guys. I really appreciate it. I plan to upgrade my engine in about a year so I only hope that it will last that long. I would do the time serts, but the tool alone is worth a quarter of what my car is worth and I will probably never use the kit again. In addition, I've only found 1 thread that shows someone using time serts on a 4.9L and the user stated that he had to cut the lip from the time serts, drill into the block a bit because of length issues and that it was a painful install (this worries me). In addition, Time Sert does not offer a tool specifically for my car (doesnt sound comforting).

This is what Time Set sent me for anyone else who may want to give it a shot:

Hello,
Sorry to say we do not have a specific kit for the 4.9L
which is a M12x1.75.
All we can offer is a longer tooling
in what we call a "universal headbolt" This is what we
have sold for the 4.9L the tooling could be slightly longer
also but it has been used without any problems.
LINK: http://www.timesert.com/html/universalheadbolt.html
p/n 4900 $445.92 kit includes all the tools and 10 inserts
of a M12x1.75x30mm length.

The core drill in the picture is about 7 inches long.
http://www.timesert.com/images/kits/...turer/d16l.jpg

beveluv · #5 (**permalink**) 10-22-09, 03:57 PM

I was told that time serts must be installed by a machine shop becasue they have to be perfectly straight. Does anyone know how true that is? I think that I might purchase the expensive kit but I dont want to buy it if the chances of me being able to perform the job correctly is slim. The nearest place to install these timeserts that I know of is in Indiana. I live in Florida, so no chance of that being an option.

beveluv · #6 (**permalink**) 10-22-09, 04:05 PM

The treads came out of my block (1992 Cadillac Deville, 4.9L) when torquing the head bolts. I need to attempt to determine if any of the other bolts will have the same issue. If I randomly(becasue 1 is already dethreaded preventing me from torquing in sequence) torque all of the other bolts to see if they will hold, will this hurt my block, gasket, or head if it will only be torqued for a few minutes? In addition, anyone know where I might be able to find a used Timesert kit? Looks like I may have to purchase one for a 1 time use ($450 bucks for 1 time usage and its not guranteed to work becasue I was told a machine shop should install them to ensure that they are perfectly straight)

**Ranger** · #7 (**permalink**) 10-22-09, 09:58 PM

The kit comes with an alignment jig so it is pretty hard not to drill the hold straight. Check Ebay for a used kit.

beveluv · #8 (**permalink**) 10-27-09, 09:27 AM

OK, So when I was attempting to install the helicoil, I noticed that the tap is going to be too short (3/4 inch). DOes anyone know where to find a very thin tap extension. The ones that I have found are to fat. In addition, the helicoil threads are not as long as the threads on the bolt. If I put the helicoil in to where the bolt normally torques to, do you suspect an issue because of the usage of very few threads in comparison to manufacture install?

00 Deville · #9 (**permalink**) 10-27-09, 12:02 PM

There's a guy over on the Seville board that's trying to sell a used Timesert kit. Don't know what he wants for it or if it would be of any help to you since he used it on a N*.

http://www.cadillacforums.com/forums...-kit-sale.html (Timesert Kit for sale)

beveluv · #10 (**permalink**) 10-27-09, 05:43 PM

Thanks for the info. I posted a reply for the link you provided. Hopefully he will get back to me soon. Until the,I will continue to look for a tap extension or maybeI can have a machine shop weld a longer piece of metal or piping to the tap. I only need 3/4 inch.

Melrose · #11 (**permalink**) 11-16-09, 01:42 PM

Cadillac recommends the Heli-coil for headbolts in the Genuine Cadillac Shop Manual, Volume I.

If you insist on using the Timesert etc. Call Beaver Drill in Mission Kansas, theyare the tool-drill provider to the American Airlines, formerly TWA repair base in KC. They have left hand right hand unusual length bits in cobalt etc. at very reasonable prices.