Sheared 6mm bolt on Water Pump

[Marccus]

Firstly

Why are there 6mm bolts and 8mm bolts on the WP?

The 8mm bolt have torque specs of 11-16 ft-lbf. From a table, the 6mm bolts have torque specs of 9 ft-lbf with ARP assembly lubricant (moly based), which I use.

The top two bolts on the WP right next to each other are 6mm bolts.

Why would you design a WP that is assymetrically loaded around its perimeter with different size bolts?

Anyways, I used a click type torque wrench. The wrench "clicked" at 9 ft-lbf for all the 6mm bolts except one. I thought something was wrong with this last bolt since it seemed to get EASIER to turn the torque wrench as I tightened the bolt.

I went back to one of the 6mm bolts that I had already torqued and the wrench "clicked". When I went back to the last bolt, the head snapped with one turn.

So I messed up.

I pressurized the system to 16 psi and I had a pressure loss of 1.25 psi over 5 minutes.

Prior to replacing the water pump I was able to hold pressure steady for two minutes.

So ..

I guess the leak must be due to the sheared 6 mm bolt?

Any other opinions?

Has anyone had to remove a sheared bolt on a WP?

The problem I see is getting enough access room to drill the bolt and use a screw extractor.

I can't use a conventional drill. I would have to buy one of those right angle drills for tight access or ...

would I have enough room if I removed the radiator and A/C condenser?

Any advice??

Thanks.

 

[Mr Anonymous]

The three small bolts secure the pump to the housing, the 4 larger bolts secure the pump assembly to the block and heads.

Personally, unless you can SEE it leaking coolant, I wouldn't worry about it. With 6 other fasteners holding the whole thing together, there should be plenty of torque on the circumference of the gasket. If it does end up leaking, you're going to have to do the same labor anyway (just later). Realistically, you're better off removing the whole pump assembly (leaving the small bolts in place) and drill out and re-tap the problem bolt on a bench.

My first ever water pump replacement many, many, many years ago I broke one of the small bolts and it never leaked. I've had cars come in with one small bolt missing or broken, and where one of the M8 bolts was snapped off and they didn't leak (from behind the pump anyway) either.

FWIW, I work on these cars every day and I pretty much only use a torque wrench for head bolts, cam cap bolts, clutches, tranny work, and lug nuts. Everything else is by feel. Plus, unless you have the torque wrench calibrated regularly, you're really just going by feel anyway. Never ever use thread sealant unless the manual calls for it, and even then it's usually just blue or red loctite. When you try to torque a wet fastener with a dry value, you're asking for trouble.

 

[itwonder]

You are over thinking things. That assembly **** probably caused you to over-torque. I prefer beam or digital torque wrenches for low torque values because it's to easy to miss the click. 1.25 psi drop over 5 minutes is not an issue. You can get a cheap angle drill at Harbor Freight, but I would probably leave it alone and fix it on the bench next WP time.

 

[Marccus]

The three small bolts secure the pump to the housing, the 4 larger bolts secure the pump assembly to the block and heads.

Personally, unless you can SEE it leaking coolant, I wouldn't worry about it. With 6 other fasteners holding the whole thing together, there should be plenty of torque on the circumference of the gasket. If it does end up leaking, you're going to have to do the same labor anyway (just later). Realistically, you're better off removing the whole pump assembly (leaving the small bolts in place) and drill out and re-tap the problem bolt on a bench.

My first ever water pump replacement many, many, many years ago I broke one of the small bolts and it never leaked. I've had cars come in with one small bolt missing or broken, and where one of the M8 bolts was snapped off and they didn't leak (from behind the pump anyway) either.

FWIW, I work on these cars every day and I pretty much only use a torque wrench for head bolts, cam cap bolts, clutches, tranny work, and lug nuts. Everything else is by feel. Plus, unless you have the torque wrench calibrated regularly, you're really just going by feel anyway. Never ever use thread sealant unless the manual calls for it, and even then it's usually just blue or red loctite. When you try to torque a wet fastener with a dry value, you're asking for trouble.

:thankyou:

Thanks very much; I wouldn't have known or thought about all you know and suggest.

"When you try to torque a wet fastener..."
Yes, I over thought things. I saw a table on the forum that had torque values for practically every bolt on the SHO.

I thought - "Wow, now I can do everything exactly as it should be done. Every fastener will be tightened to the exact value".

I saw this table and put too much gospel in it! I honestly believed I was doing "good"; that I knew what I was doing!

:booboo:

:asskick:

:idiot:

I didn't realize which bolts you really have to pay attention to for torquing and the danger you can get yourself into when torquing a wet fastener.

I wish I had heard your advice or had your PRACTICAL knowledge on what to torque rather than the "book knowledge" - the clear difference between a "doer" and a "thinker"! And I wouldn't have gotten myself into this mess!

The book never tells you what kind of trouble you mention you can get in to; life always tells you the answer and you NEVER forget!

I won't try to be so exact in doing everything I read, but rather in doing what others with experience have done.

Another way of saying it - a little bit of knowledge can be a dangerous thing, especially when I don't have that much experience using a torque wrench and in what instances to use it.

Mucho thanks for the lesson - I am humbled. :urock:

 

[Marccus]

You are over thinking things. That assembly **** probably caused you to over-torque. I prefer beam or digital torque wrenches for low torque values because it's to easy to miss the click. 1.25 psi drop over 5 minutes is not an issue. You can get a cheap angle drill at Harbor Freight, but I would probably leave it alone and fix it on the bench next WP time.

:thankyou:

Yes, I did overthink things. See my reply above. The beam torque wrench or a wrench with a digital readout would have been a better choice, since I could see that with the assembly **** on the fastener, I was not going to reach the torque value that I was aiming for.

I'll let it go and fix it next time as you suggest, because embarrassing as it is to admit; I started to work on this job (replace CPS, bottom radiator hose, water pump) on Friday at 1:00 PM and finished on Monday night at 11:30 PM ...... and I'm not going to take that WP off!!



Now I didn't work a full day every day, but like I said, it's embarassing to state how many hours this job took me.

I don't know why I'm so slow or that it takes me so much longer than I could possibly believe anyone else would have taken.

If I were a mechanic, I would be homeless and starving because I wouldn't be able to support myself!

 

[Mr Anonymous]

"When you try to torque a wet fastener..."
Yes, I over thought things. I saw a table on the forum that had torque values for practically every bolt on the SHO.

I thought - "Wow, now I can do everything exactly as it should be done. Every fastener will be tightened to the exact value".

I saw this table and put too much gospel in it! I honestly believed I was doing "good"; that I knew what I was doing!

It's not a bad thing that you tried to do things "right" but sometimes even the best plans just don't work out.

Smaller fasteners especially it's very easy to strip threads or break the bolt. I bet if you checked every fastener on the car a year after it rolled off the assembly line, a good 50% of them would not be in spec. Unfortunately, the service manual can't account for variations in knowledge and experience, so it's written in a very antiseptic fashion for the least-common denominator types. For example, on the rare occasions that a shop manual addresses a broken fastener or such, the usual solution is to replace the component when in the real world it's usually an easy fix.

For most people who don't work on cars regularly, it's usually better to be safe than sorry. Fortunately there is a lot of information accumulated on this forum that will guide people through what they would have considered an impossible task. It's just a matter of sorting through several methods to doing the exact same thing to figure out which is best and makes the most sense to the end user.

 

[itwonder]

Don't worry about it Marccus. It is a rare mechanic who has not twisted off a bolt head or pulled out some threads at some point. It's just something that happens, even to experienced guys. Steel bolts into aluminum castings are worst case.