coolant in strange place

[markko]

Hi everyone,

My 78 has developed a coolant leak in what seems to me a very strange place. Coolant pools on top of the cylinder head in the cavity adjacent to the the #1 spark plug hole. (See attached picture.) I should say that there is no evidence of a problem in the cooling system; the gauge will go up to 190 and then the fan comes on and keeps it there. There is no steam anywhere, and no smell. I can't seem to reproduce it with a hot engine and the car parked so that I can watch it. The engine is running great, and there is no oil in the coolant or vice versa. There is no obvious "trail" of coolant or other wet spots that I can see. It seems to me that the obvious source of the leak would be the bolt right in front of the cavity, but I can't see anything there. Does anyone have an idea where this might be coming from and (more importantly) how to fix it? As I said, she runs great right now, but I would like to take care of this before there is a real problem. Thanks in advance.https://imgur.com/hRndNoT

[Integrale]

My guess would be head water outlet gasket or I believe the head bolt goes into the water jacket and may be weeping up, check your head bolt torque.

[markko]

Thanks. That makes sense. I did put a socket on the head bolt, and it was very tight, so I didn’t mess with it. I’ve never messed with head bolts, and I’m a little wary of getting in over my head (based on prior experience—don’t ask). So, can I simply remove the bolt, apply some thread sealant, and tighten it up to the specified torque? Based on what I’ve seen elsewhere, this would seem to be 61 lbs.

[18Fiatsandcounting]

So, can I simply remove the bolt, apply some thread sealant, and tighten it up to the specified torque? Based on what I’ve seen elsewhere, this would seem to be 61 lbs.

Yes, I don't see any problem with removing a single bolt and doing what you describe.

However, and I can't say that I have seen all the different Fiat blocks, but all the ones that I've seen have blind holes for the head bolts, that is, they are not open to coolant. That's not to say that a previous owner couldn't have done something goofy like forget to put the washer on the bolt and then tightening it too far into the block so that it cracks the bottom open (and then touches coolant).

So, I'd work on that coolant outlet housing first. Leaks there are quite common, and sometimes the wrong gasket/seal is installed. Use care removing the 4 bolts that hold down the coolant housing. They are almost always corroded and can break.

-Bryan

[markko]

Thanks 18fiats. Please forgive my ignorance, but by coolant outlet housing, do you mean the silvery fitting between the valve covers that is attached to the timing cover? Presumably I would have to drain the coolant, yes? Can I simply loosen the 4 bolts and then lift it out of the way to install a new gasket? Or does it require further disassembly and reassembly?

[ORFORD2004]

It happen to me. You have to lower your water level and remove the 4 bolts.

[18Fiatsandcounting]

... by coolant outlet housing, do you mean the silvery fitting between the valve covers that is attached to the timing cover? Presumably I would have to drain the coolant, yes? Can I simply loosen the 4 bolts and then lift it out of the way to install a new gasket? Or does it require further disassembly and reassembly?

Yes, you have it right: the fitting right in front of the #1 spark plug well, between the two cam towers, and at the very front is a T-connection that goes to the upper radiator 2" hose and another 2" hose that goes to the thermostat. This is what it looks like, although this is for the earlier cars with the thermostat in this housing:
https://autoricambi.us/straight-coolant ... hermostat/

Remove the timing belt cover, remove the bracket at the top of the outlet that the cover was bolted to, and then all that remains is to remove the 4 bolts that hold the housing to the head. As Orford suggests, you don't have to drain the coolant, but just lower the level by a quart or so.

The gasket is more of a flat rubber o-ring, and sometimes people use 2 of them to seal. It should seal with one, but on these older cars, weird stuff can happen. Sometimes the o-ring simply shrinks and no longer seals. Here's what it looks like:
https://autoricambi.us/rubber-thermosta ... head-seal/

But, given that those 4 bolts are a source of frustration in that they sometimes break (creating a real problem), have you dried up the coolant on the head and then run the engine, to see if you can see coolant seeping out from somewhere? I just don't want you to have to remove something that isn't the problem.

-Bryan

[markko]

I have tried to spot the where the coolant is coming from, but I can’t see anything obvious. Given where the coolant pools, it would have to be either that gasket or the head bolt, and the gasket seems like a more likely culprit. I had thought that this was the proper gasket: https://autoricambi.us/rubber-thermosta ... head-seal/

[ORFORD2004]

This one i think: https://autoricambi.us/paper-thermostat ... ad-gasket/

[markko]

Thanks for all your help everyone. I’m leaving town for a couple of weeks tomorrow, and won’t be able to tackle it until I get back. I’ll let you know what happens,

[18Fiatsandcounting]

Orford is right, and there are actually 2 sealing items: The cork/rubber o-ring that you pointed out, and the paper gasket seal for the housing to the head. Both are needed.

-Bryan