TR6 Front sealing block

Developed a leak at the front of the engine and found one of the bottom holes in the aluminum sealing block is stripped. To replace this is looks like I need to strip the front of the engine all the way down and including the engine plate. I'm I correct with this assumption or can it be pulled out by removing the three bolts that go in the front of the block and the two screws and not have it leak again? It looks liked I will need to replace the timing cover gasket, engine plate gasket, sealing block gasket, wood wedges, and oil pan gasket. Does anybody have a better way?

Guess I should change the timing cover seal too.

FWIW, although I've not done that one, I have done similar repairs in place. Just run the special tap in through the hole in the timing cover, then install the Helicoil deep enough that it is entirely in the aluminum block. It will probably cut into the cover just a bit, but not enough to hurt anything.

With some care, you don't even have to drill; as the stripped part of the hole will already be very close to the right size, and the special tap will finish reaming it to size. The careful part comes in when the tap starts trying to ream the smaller part of the hole at the bottom where it isn't stripped. You'll have to take smaller cuts (ie only 1/4 turn before backing up to break the chip, and remove the tap more often to clear chips), but can be done. Be sure to quit when the tap hits bottom. Or you can drill if you want (but it's really tough to keep a hand-held drill from grabbing and twisting in the soft aluminum).

Oh yeah, pack the tap flutes with grease to help catch chips, and clean & repack every few turns.

PS, I've not tried it that way, but drilling the aluminum block would probably be easier with a drill bit designed for use in brass and other soft materials. You can buy them ready-made, or modify a standard twist drill (but it won't cut steel worth a darn once it's modified). Eg,
https://www.youtube.com/watch?v=pAngKHIZgyA

Thank you Randall. I was thinking about the helicoil method but was afraid about the chips in the engine. With the pan off it should be easy to clean. I never thought about the grease or even heard about the drill bit for brass or aluminum. I like the idea of modifying the drill bit to drill the soft metal, and the video you provided. Thank you again for the information.

HeliCoiling the sealing bar in place is difficult but can be done. Also, plan to modify the HeliCoil insert before installation. As purchased, even the shortest standard length may be too long. You will probably have to cut one or two coils off prior to insertion. Make sure that when installed the insert is below the gasket surface.

If it proves too difficult to do in place, there is a lot of work required to get the sealing plate out. You will have to pull the front pulley, timing chain cover, AND loosen the sump enough to drop it a little bit. If the sump gasket tears, that means pulling the pan off completely to replace it.

That bar should be the same for TR6, GT6, and Spitfire. You may want to get a spare bar, HeliCoil it even if it appears to be in good shape, and be ready with it just in case things go wrong.

At one time there was an eBay seller who was making and selling steel reproductions of the diecast block.

Hi Keith,

Just tore my 250 engine down yesterday...I see that my front sealing block has been stripped at one point too...

Here is the link if you want a visual on what you need to do to get to it...

https://youtu.be/70bOBcuRZWs

Cheers
Tush

dklawson said:

HeliCoiling the sealing bar in place is difficult but can be done. Also, plan to modify the HeliCoil insert before installation. As purchased, even the shortest standard length may be too long. You will probably have to cut one or two coils off prior to insertion. Make sure that when installed the insert is below the gasket surface.

If it proves too difficult to do in place, there is a lot of work required to get the sealing plate out. You will have to pull the front pulley, timing chain cover, AND loosen the sump enough to drop it a little bit. If the sump gasket tears, that means pulling the pan off completely to replace it.

That bar should be the same for TR6, GT6, and Spitfire. You may want to get a spare bar, HeliCoil it even if it appears to be in good shape, and be ready with it just in case things go wrong.

At one time there was an eBay seller who was making and selling steel reproductions of the diecast block.

Click to expand...

Here it is...

https://www.classic-technologies.com/sealing-block.php

Cheers
Tush

I replaced the block on my TR6 a while ago, in situ; I purchased the stainless steel job off the eBay seller. Worked very well. Jacked the front of the car up and removed the old one, installed the new one without removing any other components on the front of the motor. Just the oil pan. Plenty of gasket sealant did the trick.

Tush Thank you for the links. I have an extra block on hand with good threads. I'm going to try to install the helicoil, and if that does not work I may still order Classic Technologies block.

Doug: So I don't have to remove the engine plate? I'm afraid the gasket behind the engine plate against the sealing block will tear and leak. Thank you for letting me know about the length of the coils being to long.

Erich: I think the gasket material would be saturated with oil and you would not get a good seal.

One last question about the helicoils. I see they make a thread lock for them but what about the threads making a good seal and not leaking?

For the front plate, you would do as Randall suggested... drill and tap through the front plate. The hole will be oversized but that should not be a problem. Tearing the gasket is always a possibility. All you can do is work with care, go slow, and work towards keeping it intact.

For HeliCoil type inserts there are locking types where the threads are not cylindrical but sort of faceted. This creates interference points between the insert thread and the fastener. I have not used them either at work or at home but I have seen them used by others. Their advantage is that they retain the fastener without the use of products like Loctite. You won't need them here. The standard Triumph fasteners with lock washers will suffice.

As for sealing the threads, don't be too concerned about that. The gasket provides the seal. You are not counting on the threads to plug leak paths. That said, with the oversized hole drilled through the front plate, I would not hesitate to apply gasket sealant to the fasteners and their washers to seal off as many possible leak paths as possible.

Thank you Doug for the additional information. I will have a go at this this weekend.

Forget the helicoil business, I just helped a friend install the new steel block linked above and it is the correct solution. We had to remove the old block because it had been helicoiled and didn't seal properly. Do it once, and do it right. Its a pain to do twice. You can use permatex to seal the block to the front plate, when you bolt the block in you don't actually need the two retaining screws to be very tight, you want the block to move. What seals the block is the connection to the front plate, the oil pan, and the wood side blocks. The two retaining screws should just hold it close enough until everything else is in place. You cannot waste a ton of time because the permatex will dry out on you but that's how it should be done.

It's not clear what makes replacing the block the "correct" solution. By what standard or authority is it "incorrect" to repair the original block?

Many, many blocks have been repaired successfully.

Ed