Thread from Timing Cover side of therm. housing obliterated. Can this be fixed?

Hey All, brand new to the forum. Have a 97 with the 2.7L (3RZ-FE) motor. Been racking my mind about how to go about this rebuild that I’ve been working on (& off) for some time.

The threaded screw that’s on the timing cover side of the thermostat housing was broken, tried to remove it, wasn’t budging, so I cut it off and tried to drill thru the hole to get it out and ended up off center. Part of the screw is still stuck on what’s left of the threads. Picture to help visualize this (green arrow points to thread, you can still make out the original hole. Blue is the “new” hole) Other pics for context.

I want to know if there is a way to fix this somehow. I know that replacing the timing cover is ideal, however, there’s no ‘easy’ way to do it as I’d have to remove the head/cams/etc because the head gasket extends to the timing cover too. Replacing it without removing the head, from what I’ve seen, is almost impossible without running the risk of damaging the head gasket and therefore causing some major issues.

Im open to any advice and hopefully, a solution…


Thank you!

 

Is that a crack I see at the 5 o'clock of the red circle? If it is you might have some big issues.

No offense, but if you cant drill out a bolt (which I admittedly wouldn't be able to do myself), what makes you think you'll have better luck filling a blind hole by welding? Keeping in mind the surface has to be flat in order to properly seal, before drilling and re-threading the hole to the correct depth. I don't want to sound mean.

You have to consider what metals there are, aluminum has to be stick welded. Cast iron take some special care to heating the metal. And there are some metals don't play well together, and in extreme environments you can see galvanic corrosion (possible considering there is coolant around). And then you'd have to redrill and re tap the bolt hole the the correct depth. It's also a sealing surface, a head gasket can leak with only a little warping (an amount imperceptible to the naked eye). And a water pump could be the same story.

I'd say that replacing the housing is the easiest option. Get a decent shop to look at it, I could be wrong. But the most assured way you'll get a non-leaking engine is to replace the cover.

 

@Trekker To start, no it’s not a crack. Just how the photo looks, other than the issue at hand the cover is in perfect condition…no offense taken, it was one of those days where I’ve been wrenching away till the AM and made a stupid mistake. I’m usually more meticulous about doing this kind of repair, the idea was that the drill bit would help loosen the screw but said screw it and went all the way thru, thinking it was straight… I have some experience in welding, not with aluminum, but I know this would probably take some careful prep work to have an aluminum filler rod bind to the metal.. think preheating, keeping it hot, and filling the cavity, all at the same time. It’s not impossible though, so I might explore that idea a bit more.

I don’t plan on taking it to a shop, I know my last course of action would be to backtrack and just replace the cover entirely. Just wanted to put this out there to see if anyone has a trick of the trade to get this fixed or replaced without going thru the entire process. Thank you for your input!

 

I would use it as a practice piece if you want to try your skills at welding aluminum.

Regardless, expect to just replace it. Treat it as a lesson learned.

 

Sorry that this has happened to you. I suggest that you grab yourself a new part or perhaps find a replacement one at a junkyard.

 

A 3rd Gen has a thermostat? Learn something new every day.

 

Every water cooled car has one. Since like the 50's.

 

@4RunSpeed did you manage to get it repaired?

 

Since you already have a screwed part, this is my suggestion.

1. If the bolt is still in the hole (I cannot tell from the pic) you have to get that out.

2. I would jb weld the hole up. After the epoxy is in the hole, take a putty knife and wipe the gasket surface flat. Then let the epoxy cure overnight.

3. Drill out the hole.

4. Use a hex nut on the back side instead of threading the cover.

 

@Trekker
It’s been awhile since I’ve logged in…

I decided to remove the timing cover and replace with the new one. Tried installing and screwed the part of the head gasket that sits on top of the cover. So because I’m limited on time and space has become scarce, I decided to cut the bad parts and place gasket maker and throw it back on there as a very temporary fix. Once I get it registered and legal, I’ll be able to park it on the street and replace the head gasket from there. Thanks for all the help!

 

Sounds like you already did the work but permatex makes an epoxy metal "weld" that is pretty much only good for your situation, kinda like the JB weld mentioned above. You mix it, fill the damaged area and then run a tap and tap threads in it. It advertises to be good for a lot of things, that's not exactly true. But for a thermostat housing that doesn't see a lot of pressure on the threads. It works pretty good most of the time. Also, depending on how buggered out the hole is, installing a helicoil might work as well. You have to open up the hole size anyways then tap oversized for the insert.