Coolant Leak / Expansion Tank

[mge825y]

I have an active thread on replacing my radiator fan shroud. When I replace the shroud and while I have the "patient on the operating table", I think I'll go ahead and address a pesky coolant leak. What I see is a slight pooling of coolant on the back of the valley pan.

I suspect that I have a bad seal at the coolant expansion tank mount. I've searched and read many forum posts on the subject. But thought I'd ask if someone has tackled the same issue, what you ran into, and whether you found a good method for remounting the expansion tank to get rid of this pesky leak?

Thanks!

[TonyC]

I've dealt with that. If the tank itself is otherwise intact and only leaking where it mates to the intake, you want to check the condition of the mounting surface of the flange. It will usually pit; it's supposed to be smooth. Fill the pitting with JB Weld or some other coolant-resistant epoxy, sand smooth when dry, get a new gasket at the nearest part store, buy the strongest beer on the way home, install, get frustrated, drink beer to calm down, keep trying to install, torque to specs when everything is finally in place, drink a beer to toast your success.

While at it, you should check the condition of the bypass hose next to the tank flange. That'll cause leaks on the valley pan as well. If you have even slight doubt about it, you need a 3"-long piece of 7/8" hose to replace it. In a pinch, 13/16" hose can work, but it will be harder to fit onto the fittings. It's not an easy task to replace that hose without removing the water pump (ask me how I know), but it's a bit easier with the expansion tank out of the way.

If you still have a leak after all of that, then it's your intake; specifically, the expansion plugs underneath.

---Tony

[rick]

Tony,

If I tried following your instructions (when my mechanical skills are factored in) there would be so many frustration breaks, I'd end up too drunk to finish the job

[Dan Szwarc]

There should be a sticky for just changing that damn gasket on the 430s and 462s because it is a royal pain in the ass!

I’ll see if I can find some good threads from the past.

[Lee]

Mark, two other remote possibilities: leaky joint in the expansion tank (I don’t think it’s any accident that those have recently started appearing as repops) or a bad joint at the point where the overflow nipple is soldered into the cap neck. I had the latter, and it caused a bit of head scratching when I’d see green liquid on the top joints of the expansion tank, which would also run down the sides into the valley pan. Also taught me to not fill the tank so far.

[LithiumCobalt]

Horrible sucky job. I hate it. Past suggestion on making mounting easier involves sourcing studs to insert into the intake manifold before you go to mount the reservoir to give you something to line up the holes on the mount with rather than bolts that requires a lot of cussing. Then just tighten with a few nuts. Worst apart about it is trying to get the bolts lines up and tightened. It’s a four hand job usually.

[mge825y]

Horrible sucky job. I hate it. Past suggestion on making mounting easier involves sourcing studs to insert into the intake manifold before you go to mount the reservoir to give you something to line up the holes on the mount with rather than bolts that requires a lot of cussing. Then just tighten with a few nuts. Worst apart about it is trying to get the bolts lines up and tightened. It’s a four hand job usually.

I did this once several years ago and remember it being a sucky job with lots of cussing. I guess I was hoping against hope that someone figured out a better way to do it!

[1Bad55Chevy]

I've dealt with that. If the tank itself is otherwise intact and only leaking where it mates to the intake, you want to check the condition of the mounting surface of the flange. It will usually pit; it's supposed to be smooth. Fill the pitting with JB Weld or some other coolant-resistant epoxy, sand smooth when dry, get a new gasket at the nearest part store, buy the strongest beer on the way home, install, get frustrated, drink beer to calm down, keep trying to install, torque to specs when everything is finally in place, drink a beer to toast your success.

While at it, you should check the condition of the bypass hose next to the tank flange. That'll cause leaks on the valley pan as well. If you have even slight doubt about it, you need a 3"-long piece of 7/8" hose to replace it. In a pinch, 13/16" hose can work, but it will be harder to fit onto the fittings. It's not an easy task to replace that hose without removing the water pump (ask me how I know), but it's a bit easier with the expansion tank out of the way.

If you still have a leak after all of that, then it's your intake; specifically, the expansion plugs underneath.

---Tony

This is how Tony does it! 14%ers hit pretty hard!

[TonyC]

Tony,

If I tried following your instructions (when my mechanical skills are factored in) there would be so many frustration breaks, I'd end up too drunk to finish the job

This is how Tony does it! 14%ers hit pretty hard!

If only...! I'm always stone-sober when I do my jobs, and with my temperament that does not always fare too well. I ought to clarify, the job is not complex; but that is not to say it's easy. I have to concur with the consensus, it's anything but! That has to be one of the main reasons that expansion tanks ceased to exist after M-Y '67.

But everybody else here has an advantage over me: They have additional means of motorized conveyance to get them through life outside the garage (heck, I don't even have a garage!), so that sort of fix isn't actually pressing. Me, every day that passes with an undone job is serious, so I'd have to be sure my on-hand domestic stocks can handle the time, which could be stretched depending on weather. On the other hand, with no other transpo option to rely on, that just motivates me more to get the job done, fast if possible but properly most of all...although on rare occasions a fast option was my only practical option .

---Tony

[papawayne]

I still think it takes two days: one to glue the gaskets on and another to put the tank and thermostat on. Or not. Wayne

[Dan Szwarc]

My tip is to use RTV black on both sides of the gasket, bolt it all up and let it sit for 24hrs minimum before putting in coolant.

[Lee]

Dan’s method is my method. It’s been a topic in the past, but I also swear by the method of drilling some air release holes in the thermostat flange, and do that on all my cars. I think you also get the benefit of a slightly faster reacting thermostat, since it keeps a small amount of heated coolant flowing past the bulb.

Tony, I bet the Ford engineers would tell you that the “expansion tank” wasn’t exactly eliminated in 68, it was simply moved to the radiator. Which was probably a bone of contention, since it effectively reduces the radiator cooling capacity to some degree on a cross flow rad.

[TonyC]

That's something I normally do myself with new thermostats: Drill a small hole for that purpose. I thought about that when I once got a thermostat done that way; that one also had a movable plug installed in the hole, but I figured such a hole could prove beneficial in reducing the chance of a coolant dump should the thermostat eventually seize up. I can't remember if I did that with the last one, but it's a trick I endorse. Just don't make it a large hole, or it could compromise engine warming in cold weather.

---Tony

[Dan Szwarc]

Some newer Thermostats have that little hole. Remember that 60s Lincolns have that bypass tube into the intake, and are actually circulating coolant through the intake and heads (with or without the stupid block thermostats) to heat up as quickly as possible.

There’s no shortage of a source of heat on a 430 or 462. Mine heats up way too damn quickly but has never overheated in even 95 degree weather.

[mge825y]

Well, I was called away this summer and never did have the time to remove and remount my coolant expansion tank like I planned. But it's still on my list. Then was called away again and got home a few weeks ago. Since I have been out of town, I have not cranked nor driven my '63 since October.

Then last week, temperatures here dropped down in the 14 to 18 degree range for a few nights. My home's garage where the '63 Lincoln is parked is unheated and not well insulated.

After the cold weather moved out, I went out in the garage and found two streams of a coolant on the garage floor under the car. I mopped them up and they have reappeared. I know that they were not there before the cold temps last week. I crawled around the car with flashlights and It looks like that the coolant is dripping down onto the floor from either side of the bottom of the bell housing. Higher up, the valley pan does have coolant on it and it sorta looks like it maybe dripping down to the top of the bell housing and then down both sides of the bell housing until it drips on the floor. I'm running 50/50 NAPA green coolant that was new after the 2020 rebuild that has been topped off several times. I checked all fluids in the car when I drove it last October and I topped off the coolant then too.

Could the recent cold temps somehow make the existing drip from the expansion tank to valley pan worse? Or, do you think I have something else going on (like a leaking freeze plug) ? Again, the car is at rest and hasn't moved or been cranked since October so nothing is moving / circulating the coolant.

I did check the expansion tank today and it only has a little coolant in it, but not alot. So, I wiped off the valley pan and the garage floor and am trying to keep an eye on it.

I would welcome your thoughts on what this might be.