Loose bolt at coolant T outlet, help with size and diagnosing problem

[QuintupleTurbo]

Hey everyone!

Happy to be here. I still need to post my intro, but first, I could use your help diagnosing an issue. I just bought a beautiful 1971 124 Spider last week, that has an engine and cooling from a 1979. I had it thoroughly inspected by a Fiat specialist, as well as with the eyes of the excellent forum member who sold it to me, and there were a few leaks that were addressed. However, I think some bolts came loose from its time on the flatbed, and one of them I'm having an issue with.

Had to get him out of the garage for a few minutes, and when I pulled back in, I noticed a pretty considerable amount of coolant dripping down. I took a look at the source, and one of the bolts on the bottom of the coolant outlet was loose. I put my hand down and the bolt came straight out, and then also went back in. I grabbed my sockets and wasn't able to get the bolt to catch. Not sure where the threads catch, but the inside was pretty gunked up (Loctite or some kind of waterproofing sealant?)

I've attached some pictures in an imgur album to make it easier.

https://imgur.com/a/AUwv76X

Here's a few questions that I have, that hopefully you guys can help with.

• 1) Did the tip of this bolt break off inside? Unsure of the set length of these bolts.
  2) I see listings online of 1979 Coolant Outlets, but I'm unsure of what the specs are on these bolts if I just need a replacement.
  3) Is there documentation for how heavy these bolts should be torqued? I was reading through the shop manual, and didn't see anything for these very specific bolts.

I'd appreciate any info that you guys can provide.

Thank you!!

[Nut124]

The bolt looks to be about the right length. I suspect someone over tightened and stripped the threads in the outlet.

I believe that is an M6 bolt. I have not seen a torque spec. M8 bolts in the head call for 14-15 ft-lbs, so this M6 should be well below 10 ft-lbs, perhaps 5-7.

You might be able to drill and tap the hole deeper, not sure, might drill into coolant. Could be worth a try if you can get a drill on it w/o removing the part. If you drill into water, you'd want to use a copper sealing washer under the bolt head and/or thread sealer.

[18Fiatsandcounting]

First off: Man, that is one sweet looking '71 spider! I also have a '71 but it's paint is, shall we say, an embarrassment...

I don't think it will be too hard to fix your bolt issue. These bolts are M6x1.0, and they are not tightened very much. 6 or 7 ft lbs at most. Someone probably overtorqued it in the past and stripped the threads, and then tried to repair it.

The first step would be to remove the T-connection. Clean out the upper and lower bolt holes as best you can. Too bad the issue is not with the upper bolt as you could just get a longer bolt and then put a nut on the other end to hold it. But, the lower bolt hole is a blind hole.

My first attempt would be to try a longer M6x1.0 bolt. Clean out the existing hole with a thread chaser or the like, and see if there are still some threads at the bottom to grip with the longer bolt. If that doesn't turn out, you have three options. One, you could fill in the bolt hole with metal epoxy and then retap new threads. Two, you could retap the hole for a larger bolt, although it might have to SAE rather than metric. Option #3 is to buy a new thermostat housing like this:
https://www.midwest-bayless.com/Fiat-12 ... 80-u9.aspx

In my opinion, Option #3 is the best, Option #2 will work, and Option #1 is less reliable. Let us know how it progresses!

And I see that Nut beat me to a response, so let's see how my unedited response compares to his!

-Bryan

[QuintupleTurbo]

Thanks a bunch for your help!

This car is an absolute beauty. I've gotten non-stop thumbs up and questions about it in the storied 7 days of it being in my garage

Going to start off by getting that blind hole cleaned up and see if anything is salvageable in there. I found an M6 bolt at the store that's about 2mm longer, so we'll see if there's any luck!

I'll keep you all posted on how it goes. I'll try to get some pictures on here too so it can be documented in case anyone else has this issue.

[QuintupleTurbo]

An update:

Tried getting in there with a thread chaser and some lube, but the thread chaser couldn't even catch the threads past a certain point, so I'm guessing that they'd need retapped.

Bryan, I ended up ordering that new part from midwest-bayless, along with the replacement gasket, so I'll be tackling that as soon as it arrives.

This will be my first endeavor into work like this, so I may be leaning on the forum for guidance so I don't muck anything up

I'm assuming I'll need to drain the coolant, at least to a certain level, remove the timing belt cover, remove the tee from the outlet, remove the outlet, clean up the connecting point of the tee, replace the gasket, and then replace the outlet. There's a burp valve installed on the heater hose, so once I refill I can bleed everything from there.

Anything else I should pick up to ensure a proper seal? It looks like Permatex #2 could create an additional seal around the gasket where the tee meets the outlet. I'm wondering if I need to put anything additional where the outlet meets the seal. I'll use a little brake cleaner on a rag to clean up the connecting points for all of these parts.

I'm looking through as many manuals as I can find to determine proper torque values for these bolts so I don't screw up anything additionally It looks like maybe two M8 bolts connect the outlet to the head, and then the two M6 bolts that connect the tee to the outlet.

I'm thinking maybe a little loctite 242 on the ends of the threads to make sure they're in there good, but I'll take advice from the panel on how to best proceed!

Thanks again.

EDIT: I'll also add some photos of the process for folks that may need to do this same job in the future.

[kilrwail]

There's a table available on line which shows the maximum torque values for all sizes of metric bolts, in the different grades available. M6 has a maximum of 13 ft-lbs in Grade 12.9 and a max of 7.5 in Grade 8.8 or 9.8. Sorry I can't tell you where I found the table, but it's really handy.

[18Fiatsandcounting]

I'm assuming I'll need to drain the coolant, at least to a certain level, remove the timing belt cover, remove the tee from the outlet, remove the outlet, clean up the connecting point of the tee, replace the gasket, and then replace the outlet. There's a burp valve installed on the heater hose, so once I refill I can bleed everything from there.

Yes, you've got it right, this is the approach. Remember that there is a gasket between the outlet and the cylinder head, and the gasket "style" depends on model year. There are also 4 bolts holding the outlet to the cylinder head: 2 shorter M6x1.0 and 2 longer M6x1.0. These can be corroded, so go very carefully as they have an annoying tendency to snap off and then you have a bigger problem.

I personally don't use any thread sealant or Permatex. If the sealing surfaces are good, and you have a new gasket, that should be all you need. For the sealing surfaces, I lightly clean them up with a sanding block and 220 grit sandpaper or the like. At a minimum, remove all the coolant "crud" that tends to form over the years.

I would NOT use Loctite on any of the bolts, as they can be hard enough to remove and you don't want to make things any harder should you need to take it apart in the future. And, as kilrwail points out, 7 or 8 ft lbs is the most you want to put on these M6 bolts. 6 would probably be enough.

Thank you in advance for any pictures you might post. Hope it all works out!

-Bryan

[QuintupleTurbo]

Finally able to get to this today. I've got plenty of photos to document my progress, and will include a little guide for future spider owners.

Bryan, (Or others) question for you.

Is there a year where there wasn't a gasket between the outlet and the head? I just pulled the old outlet off and there's no gasket there. I can send some photos in a few minutes, but the original outlet and it's replacement are the exact same size. I'll drop the gasket in regardless to see how the fitment is, but there certainly was not one in here to begin with.

Going to head into the garage and take a few photos.

[QuintupleTurbo]

Added a few photos to the album below. They're the last 4 photos.

https://imgur.com/a/AUwv76X

[QuintupleTurbo]

I’m wondering if the old gasket was paper. I took the coolant out of the head and didn’t see the gasket down there. Going to seat the outlet and see how things go!

[18Fiatsandcounting]

Your new outlet looks good! Yes, there were some variations in the gasket-ing of this outlet to the head. Your '71 has an external thermostat, and so you need a rubber seal in the recess in the head, like you show in the pictures. However, there is also a paper gasket that goes around the 4 bolt holes and it looks like this:
https://autoricambi.us/paper-thermostat ... ad-gasket/

I've seen people use either the rubber seal or the paper gasket alone, and it seems to work, but I think the correct way is both a rubber seal and a gasket. However, depending on how thick that rubber seal is, sometimes you can't get the flange at the base of the outlet to get tight against the head, and so they skip the seal or skip the gasket. I guess you just have to experiment to see what looks like it would seal. If you have both a new paper gasket and new seal, I'd try and use them.

Hope this answers your question. This is going to be so awesome to get your sweet-looking spider on the road again!

Pro-tip: Clean out the 4 bolt holes in the head. I wouldn't use a thread tap, but just blow them out with compressed air or maybe run a good bolt up and down the boltholes a couple times, perhaps with a touch of oil.

-Bryan

[wetminkey]

Just wanted to say that I've been following along and that IS a beautiful Spider, plus, I also use the "Pro Tip" that Bryan recommends! It has worked perfectly for me for over 50 years,...
Best of luck with your repair! Happy Motoring!
Todd.

[QuintupleTurbo]

Thanks to both of you!

An air compressor is still on my list of things to buy as a recent transplant from New York City, and it seems like every store in Marin County is sold out of canned air. I got in there pretty good with a pipe cleaner and whatnot and all four bolts threaded up just fine.

Also, I cleaned up the head, plopped the rubber gasket in there, and the outlet got threaded in very easily.

Getting everything dialed in tomorrow morning, then I'll get some pics posted up!

[18Fiatsandcounting]

it seems like every store in Marin County is sold out of canned air.

Marin County, as in north of San Francisco? If that's the case, I'm about an hour* or so away and would love to see the car sometime. In any case, let us know how it turns out.
*with traffic, a more honest answer is two hours.

-Bryan

[QuintupleTurbo]

Hey everyone! It's been a whirlwind since I worked on this with the holidays. Hope everyone enjoyed theirs. It ended up being a snapped bolt in that blind hole! That's why I couldn't catch any threads, and had a hell of a time seeing in there.

I ended up getting the outlet swapped out without taking the timing belt cover off. It just took a little bit of jimmying The only downsides I suppose is that I was only able to get one of the small hex screws that connected the camshift timing pointer bracket to the coolant outlet. I'm assuming this is okay since there's already two nuts that connect the bracket to the belt cover.

The other downside is that it seems that some threads had broken off of some of the longer bolts that came out of the head as well. Still plenty of threads to grab on and keep the outlet tight, I haven't seen a drop of coolant since. Hoping that won't come back to bite me anytime soon!

I'm guessing the culprit for those snapped bolts is that someone had over torqued them previously. I think I did every bolt at 5 ftlb to be sure. I ended up using an inch-pounds torque wrench, because I could tell my ftlb torque wrench wasn't stopping even when it was set at 5 ftlb. Wondering if the PO had good intentions of torquing them correctly, but used a ftlb torque wrench that ended up over-tightening.

Also, I took a bunch of photos but Apple ended up changing a setting in my iPhone that switched the format of my photos to an Apple-exclusive format, which isn't compatible with any uploading service. Gotta love them! I've got to find out if I can convert those files to a regular format to upload them in case future folks want to see how I did it.

All went well though. Strangely, there wasn't an O-Ring when I removed the outlet from the head, but I put one in there anyway and mounted it up.