And...the coolant leak

[rodo]

Just finished buttoning up things: new waterpump, pulley, belt, new hoses, all together, everything beautiful and...now it appears I have a small leak from my heater pipe, the one that bolts up behind the water pump. Not sure what happened there as I cleaned, then put a new gasket, and even used some blue silicone (tiny bit) but apparently to no avail. So, it sure appears totally jammed in behind the intake. Looks like I need to take half of whatever apart again to get to either cleaning/new gasket/silicone or new pipe. Or maybe someone has some nifty trick...like I just smear half a tube of silicone around it...or...I don't know.

[18Fiatsandcounting]

Just to make sure I'm following you here: the leak is from the metal pipe that connects to the side of the water pump intake opening, runs under the exhaust manifold to the back of the engine, where this metal tube then connects to a rubber hose that goes in through the firewall to the heater core inside the car? The metal tube that looks like this:
https://www.midwest-bayless.com/FIAT-12 ... 5-u85.aspx

If the leak is from this heater pipe, it's pretty common for these to rust out from the inside and spring a leak. You might be able to have it repaired, but the better solution by far is to get a new pipe.

-Bryan

[rodo]

Correct. (Sorry, I said it was under the intake but it is the exhaust manifold.) It looks to be leaking from the flange, like maybe it is not flat enough. Hadn't thought about it rusting. But whatever the case, can it be removed without taking too much apart or am I in for a huge job?

[RRoller123]

It isn't too bad, but the coolant must be drained and makes a poisonous mess in general. The vendors sell a SS replacement, that I thought was a good idea, do it once and that should be it.

[TX82FIAT]

That pipe is somewhat sensitive where it bolts to the water pump. The ears can be bent if over torqued. I had to remove mine at one point and flatten/straighten the ears for a flush surface match. A gasket and a little RTV can help if used modestly. If you use RTV follow the instructions to the letter. With a gasket, sometimes less RTV or even none is better.

[18Fiatsandcounting]

I'll second what was said above regarding the relative ease of replacing this pipe, the use of SS, and checking the flatness of the mounting flange. In addition to rusting from inside, the pipes sometimes spring a leak where they are welded to the flange that attaches to the water pump. If this pipe has never been replaced, it's probably a good idea to get a new one, especially if you go to the trouble of removing the old one. And a new gasket for the flange to the water pump.

If you do replace the pipe, make sure that the metal clamp that goes around the pipe at midpoint is still there. This clamp attaches to the middle stud of the 5 exhaust manifold mounting studs and keeps the pipe from bending as the engine shifts back and forth, which could cause the flange weld to fail prematurely.

-Bryan

[rodo]

Amazing help all, thanks very much. I'll tuck into the pleasures of restoration...but after the holidays so as to maintain my marital status.

[RRoller123]

+1, absolutely correct. Even the smallest angle at that plate sends the far end flying away from its target point. Plus the two sides of the mounting plate were not quite coplanar on mine, needed RTV (and I think a gasket was included if I remember correctly?)

That pipe is somewhat sensitive where it bolts to the water pump. The ears can be bent if over torqued. I had to remove mine at one point and flatten/straighten the ears for a flush surface match. A gasket and a little RTV can help if used modestly. If you use RTV follow the instructions to the letter. With a gasket, sometimes less RTV or even none is better.

[DieselSpider]

With RTV remember to apply, lightly and evenly tighten the bolts to get some even squish and then allow the specified time for the RTV to harden at that thickness before tightening to final torque.

[SteinOnkel]

When I did this job a few months ago, my timing belt kit (from AR*, I believe) came with new, tiny m4 studs. I replaced the old ones and had a bit of trouble getting the nuts to tighten properly, because the studs themselves were loose. You need to put two nuts onto one stud, lock them together (you will need two wrenches for this). Then screw in the stud by hand, and tighten the nut that's furthest out. Be careful, it's only m4. Then while holding the inner nut with a wrench, loosen the outer one and spin both out by hand.

A little tricky, but it can be done.

Also get yourself a radiator cap test kit from your local auto store. It makes bleeding the system easier and detecting leaks can be done while everything is cold. Just pop off your radiator cap, connect the tool, pressurize the system to whatever your cap is rated to and wait. It should hold pressure indefinitely. If the needle drops, you've got a leak somewhere.

Cheers
Steiny

P.S: *also, the gasket for this piece immediately failed. So I sanded both surfaces down and used liquid gasket.

[Spider951]

I have found that using a cork gasket between the water pump and the metal heater pipe stops the pesky leak problem. Of course, as others have said, it is also good to start with a flat surface on the pipe flange (I sanded it flat), but I have found that the pipe "ears" are prone to bend a little upon tightening the nuts regardless of what you do ( possible design flaw IMO). The thicker, more flexible cork gasket helps to take up some of space created in the bend. Plus, with cork you don't need to tighten the two nuts quite as much. I also coat both sides of the cork with a very thin layer of petroleum jelly (may be unnecessary, but did it anyway). I couldn't find a ready-made cork gasket, but you can easily make your own with a little patience and a sharp pocket knife. Most auto parts stores sell rolls of cork gasket.

[rodo]

Spider951, when you used the cork gasket did you also use a sealant? Just the petroleum jelly? I rummaged around today and got the pipe unbolted but not removed. (I'm attempting to revive an original turbo...and it is in the way.) I checked and with a straight edge both the waterpump (of course) and the pipe appear flat. (And no rust, nothing splitting at the seam.) I think I did a poor job when installing the waterpump with not even silicone application. The cork seems the route for me. But dang, don't ever want to have to mess with this again.

[Spider951]

I just smeared a very thin layer of petroleum jelly on both sides of the cork gasket; I used no other sealant. As I recall, my logic (?) was that the petroleum jelly might squeeze into the cork a very slight distance. And I also had some very minor pitting on the pipe flange (which you apparently don't have).
BTW this is on a an '82 engine that I am using as a replacement for the OE '81 engine in my '81 car; the pipe on the '82 does not have the bracket that bolts to the manifold. I kind of worried about the lack of the bracket, but I now think the bracket may do more harm than good in holding the heater pipe flush with the back of the water pump. Maybe the Fiat engineers had come to that conclusion by 1982 ?? I would like to know what has been the experience of others that have the bracket-less heater pipe.
However, I think that regardless of sealant vs no sealant, bracket vs no bracket, the main thing is to have a thick and compressible enough gasket to make the fitting water tight when you tighten down the nuts. I haven't had much luck with the thin gaskets that typically come with new water pumps - I fought that battle several times on my '81 engine before I decided to use cork. Also, do not overtighten the nuts!!

[rodo]

Mine is an '81, with the bracket. I never knew that about the change up. I'd like to know others' experiences, too.

When I get the cork sorted, and pressure test the system, I'll post here with the results.

[rodo]

Spider951, cork is best, most durable? Just had a look at the choices. Rubber not better? Auto store had a variety of sheets and thicknesses of cork, rubber, and some kind of paper that is probably more like the oe gaskets.