Tips for removing stuck alternator/water pump bolt?
 

My alternator failed (about 99k miles) so I'm replacing it, and I'm having trouble removing the bolt that holds the alternator mounting bracket.

https://www.atkinsrotary.com/store/9...A1-18-397.html

I was able to get the alternator out without removing the bracket, but I'm concerned this bolt is going to cause problems later if I don't remove & replace it with a new one. Looking closely I'm not sure if the bolt was clamping the bracket and water pump very tightly in the first place, it looks like it might have been bottomed out in the engine. I haven't noticed coolant leaks, so I suspect the water pump gasket is sealing well enough. If anyone has some tips I'm all ears. When I twist pretty hard with a socket wrench it feels like I'm going to shear the bolt. I've tried a Milwaukee electric impact gun, I stopped after letting it hammer for a good 10-15 seconds without noticeable movement. After I called it a night I realized I have a torque wrench so I could stop at the factory torque spec for the bolt (or some higher multiple like 1.5x or 2.0x). I'm also considering unbolting all the other bolts & nuts that hold the water pump on and trying to shoot some PB Blaster in there.

To mitigate the risk entirely, cut the head off and remove the water pump housing from around it. It will be much easier to remove the huge stud left behind than dealing with what you have going on. It you keep trying to get it out and it snaps then you will be removing the water pump housing anyway. Get ahead of it and do it yourself.

With the housing off you can heat the iron and pb blast the hell out of it. You can also use a stud extractor or a hefty set of vice grips. Worst case is you can snap the very bottom of the bolt into the iron and then you HAVE to drill it out and won't have any protruding stud to grip on to.

So in short lol cut the head off and remove the water pump housing. You'll get it out

Hitting a stuck bolt directly on the head with a hammer or similar often loosens thread corrosion or other friction-causing stuff and lets it be extracted. That's similar in function to using one of those twist-impact tools. I've found it usually works well for me.

Pulling the water pump housing is a pain but doable. I would prepare to put the car down for a week or so for the job in case you have other broken stuff that you have to order.

I would have on hand -

- That bolt that's goofed up
- New water pump
- Water pump housing to block gasket
- Water pump to water pump housing gasket

Drain coolant, get the alternator and belts out of the way. Also be very careful with the OMP lines and wiring, they run underneath the water pump housing and there's a clip there that holds them in place. If need be get a good flashlight and mirror to see them and make sure you don't damage them on the way out.

May also help to put some heat on the part of the iron block that bolt goes into.

Any bolt that can possibly come in contact with water or coolant you always want to put anti-seize on. I've been doing that for years and it's always paid off long term.

Dale

Maybe not for the OP’s particular situation, but this does work well in a lot of others. I’ve even used a blunted tip on an air chisel. Also works great getting the rusty splined ends of our axles out of their hubs.
In both cases and especially with aluminum threads I use a little anti seize going back on.

Thanks for the advice, all. I've made some progress, but not out of the woods yet. I drilled the head off the bolt using a strong magnet to catch most of the metal, but there seems to be a lot of corrosion sticking the bolt to the water pump housing.
https://cimg6.ibsrv.net/gimg/www.rx7...af828c7895.jpg
Removed the head from this stuck bolt.
https://cimg7.ibsrv.net/gimg/www.rx7...9e9f3d2c72.jpg
All studs removed, but corrosion is still holding the WP housing to this headless bolt.


I've been spraying PB blaster in the hole and then rotating the housing (with all the other bolts & studs removed) to work it loose, then spraying compressed air into the hole to get the gunk out. It's slow going, hopefully I'll have some progress to report soon. I also got some Evapo-Rust after searching online for rust removers that might be safe to leave overnight, I'm planning to spray some of that on if it's still stuck before bedtime tonight.

I don't have a torch or a welder, but might try adding a heat gun to the process.

There will definitely be some anti-sieze involved in the reinstall process, and possibly some hylomar-style non-hardening gasket goop as well. One of the smaller water pump mounting bolts broke while removing it also.

parts stores sell those handheld propane torches for not very much. get one of those. with a heat gun youll just be trying to cook a steak in the shower

Quick update, I tried a propane torch but was not very successful. There's a good chance that is user error, but in my defense the bolt is very long and losing a lot of heat to the aluminum housing. I've been able to remove some of the corrosion by spraying Evapo-Rust and scraping /poking with an icepick or a small length of welding rod, but it's slow going. The corrosion/rust is holding the bolt to the water pump housing, but I can rotate the water pump housing about 1/8 to 1/4 turn in either direction so the bolt threads don't seem to be stuck in the front iron. Once I realized the bolt threads were not stuck, I tried again with a stud extractor which sheared the bolt in half. I'm slowly drilling the rest of the bolt out, using a borescope to watch that the drill bit is centered well enough to avoid trashing the pump housing.


It's starting to sink in that this poor car is getting old. What's killing me is I replaced the OEM engine with a JDM pullout about 10 years ago and I can't remember if this is the US pump housing or the JDM one. I'm wondering if I'm fighting 10 years worth of rust because of a mistake I made, or 20-25 years of rust that I missed when things were apart 10 years ago.

Update in case anyone is following along, I got the old bolt out by spending a lot of time drilling. I couldn't get the housing away from the bolt even when there was just an inch of bolt remaining. It came off with about 0.5" of bolt protruding, which wasn't enough to work with a stud extractor, so I drilled some more. In hindsight I should have been using a left-handed drill bit for most of the drilling since it would try to loosen the original bolt the entire time rather than tighten it while cutting. It turns out left-hand drill bits were in stock at a local industrial hardware supply shop (bit more specialized than Ace or Home Depot), and reasonably priced. I also learned about straight extractors and carbide dremel bits. Even when there were just small slivers of steel bolt remaining, it was really stuck to the original iron threads. A tapered extractor grabbed the old steel well enough to expose some of the first few threads in the iron, then I used a M8x1.25 tap to carefully clean up the original threads. Backup plan was a Helicoil, but I'm afraid it would have been tricky to drill the new hold at the correct angle.

A new bolt is on order (hooray for Ray Crowe), as well as a new water pump housing and gasket. One of the studs had some surface corrosion, but it looks like those aren't available from Mazda and I'm having trouble finding similar studs from McMaster or Fastenal. I think I can clean up my old stud well enough using this Evapo-Rust stuff, but it would be nice to have a backup plan. I do wonder if a bolt is the correct fastener for that part in the first place. If a stud existed in the right length, I think it would make sense to try that instead.

I'm also interested to hear people's thoughts about sealing the gasket between the water pump housing and front iron. The old gasket on my engine looked pretty sad, it may have been 20+ years old. I've seen threads suggesting grey or black RTV (Honda-Bond, Right Stuff). This stuff caught my eye last time I was at the parts store, a friend who is an old-school piston engine guy said it reminds him of sealants used on aircraft engines. https://www.permatex.com/products/ga...asket-sealant/

Glad you got it out! I'm sure that was a chore!

I just use grey RTV on the coolant gaskets, I've never had a failure. The Permatex grey from the parts store. Smear a THIN coat on both sides of the gasket, that's all it needs, and make sure both mating surfaces are totally clean and flat, no old gasket or anything on it.

There is a shim that goes between the water pump housing and the block, it goes around the 2 left most studs (when looking from the front of the car) - make sure you have that there, it compensates for the gasket thickness and if it's not there that rear gasket may not seal.

Not sure on a source for the water pump studs, you may want to search around some on that.

Dale

Is it normal for the stud that holds the alternator bracket to the water pump housing to weep coolant? I don't recall it doing so the last time I removed the alternator, so I am trying to check my sanity

it shouldn't, although if you loosen that bolt it can cause seeping. a little sealant on the thread will probably fix it

When ever replacing the WP or rebuilding an engine, always use some form of anti-seize in this area do to high moisture or leakage.
Also retread all the fasteners to clean them up first.
I learnt this back in the 90s.

It's just weird because I'm pretty sure it didn't seep when I took everything apart for coating once upon a time. I have things apart now because of the fuel smells under the manifold.

this tip will only help you going forward;

buy a can of high temperature nickel-based anti-seize and use it on any threaded part not requiring thread locker instead. Same for any surfaces that tend to seize up, or inside suspension bushing sleeves that have internal cam adjuster bolts (not on the external cam washers though), etc.
.

Lol sorry if I gave the impression I am not heeding any advice. Antiseize is one of the first few things I bought for this project. I have a hate corrosion...and have a thing for longevity. I powdercoat as much as I can that won't cause trouble, but it drains my pockets on top of the fd lol.

I haven't seen this suggested in the RX7 service manual, but I think it might be wise to go back and re-torque the water pump fasteners after some time and heat cycles. The Mazda service manual specifies 19-25 Nm (14-18 ft*lbs) for the alternator/WP bolt and 18-26 Nm (14-19 ft*lbs) for the nuts. I didn't remove the water pulley, but the ones I was able to reach were around 14-18 Nm today (it's been over 1 year). It might not be enough difference to be a problem, but I torqued them back near the minimum recommended values.

I did add anti-seize to the smooth parts of the bolts and studs when reinstalling. And a thin layer of non-hardening Permatex gasket sealant #80062 to each side of the OEM water pump gasket. So far so good, there don't seem to be any leaks or seepage.

I don't think the bolts really need a re-torquing, I don't think that will get you anything.

Any bolt that has possibility of coolant contact I always get a coat of anti-seize on it. Simple step that makes life SO much easier. Thermostat bolts, water pump bolts, etc.

Dale