Gasket for coolant overflow cap?

[dyeager535]

Do they sell just the gasket at auto parts stores?

Noticed mine was torn, thus losing coolant as it sloshed around.

Not averse to buying the gasket material and making it myself, just not sure what type of material to use. Appeared to be a paper type gasket originally.

 

[diesel4me]

I dont think they sell the gasket alone--but Dorman probably sells a replacement cap for the overflow bottle...

You could make a gasket out of paper gasket material,or maybe an old rubber inner tube (I've used large tube patches for gaskets before!)--maybe an O-ring would work too?..or you could look on other bottle caps for a gasket,like off a bleach bottle,anti-freeze jug,or a gallon of motor oil perhaps...

You might be able to make a gasket from RTV too,by spreading some inside the cap and letting it harden up overnight before re-installing it..

 

[dyeager535]

I like the inner tube idea...since both surfaces are plastic I'm thinking it would be flexible and just thick enough to seal any imperfections in the mating surfaces.

I saw the new caps, I'd trust those to work until the first time I had to re-tighten it, at which point it would crack lol.

Delco sells replacements too, ~$6.50. Not ridiculous, but once I find a place local that will sell it, tax, driving, etc., just easier to make my own.

 

[dhcomp]

Um, its an openly vented cap.

I'd guess that is where you sloshing is coming out. Not through the seal.

The seal is like a little foam piece you would find in a gear lube or car wash jug.

New caps are available at the parts store, but take a closer look. I think you'll realize that its essentially an open cap.

 

[dyeager535]

I actually plugged 3 of the 4 the vents thinking that was the issue, which it is if you have too much coolant in the overflow.

With the cap dried off, and proper fluid level, after driving it still has coolant streaming down the sides and the inner fender, it's clearly coming through the threads.

My buddy was out in the woods with me, has the same overflow, his was coming out the vents.

I do find it odd that I even have this problem, it's not like I'm catching air or anything...potholes on logging roads, that's it.

 

[dhcomp]

I actually plugged 3 of the 4 the vents thinking that was the issue, which it is if you have too much coolant in the overflow.

With the cap dried off, and proper fluid level, after driving it still has coolant streaming down the sides and the inner fender, it's clearly coming through the threads.

My buddy was out in the woods with me, has the same overflow, his was coming out the vents.

I do find it odd that I even have this problem, it's not like I'm catching air or anything...potholes on logging roads, that's it.

Something sounds wrong here.

Have you check to see if its bubbling while running?

I ran without a cap for a quite a while, with no ill effects.

This overflow tank is just that, an overflow tank. Unless something weird is going on, it should just hold fluid.

 

[dyeager535]

Yeah no bubbling or anything. As simple as the system is, I agree, it seems like something different is going on, but only thing I can think of that might make this happen is the radiator cap sticking and letting go violently? Not something I can watch all the time, never seems to have any problem with the truck idling.

Seems unlikely it's letting go with a bunch of pressure randomly, but I suppose I could change radiator cap and see what happens. Annoying problem, I only recently realized where my fluid seems to be going.

 

[paratrooper307]

You're probably venting coolant into the overflow when hot, causing it to be overfull and slosh out. Might be time for a new radiator cap.

 

[dyeager535]

It's definitely not an overfull condition, the "cold" level is now correct, but still losing fluid.

When I overfilled the reservoir intentionally, it was clearly coming out the vent holes, but the reservoir never did get full. Just closer to the top.

I could let it idle and get up to ~212* to see if the cap vents violently, but that's the only possibility I can think of, that I can't discount at this point.

 

[4X4HIGH]

Do you have an overflow tank or a recovery tank? I just posted on this elsewhere tonight as well. There is a difference between the two and each require a specific radiator cap for each type of system. If you have a cap for an overflow system on a recovery tank then the tank will fill up and spill out the vent and never get sucked back into the cooling system.

 

[EXJAY]

Something to try anyways..Had the same issue on my old 84 S-10 Blazer though haven't notices any leaking on my K5 now. I ended up finding pieces of the old gasket material floating around (and in the bottom clogging the tube) in the over flow tank. Removed the tank and flushed it out then made a new gasket out of a 12pk cardboard box (cant recall but it was like a soda or beer box but it was pretty stiff). Held up well for a couple years until I sold it off.

 

[dyeager535]

It's just a stock overflow, and that's why I think peopel are questioning if something else is up...from the design I could see losing coolant out of it if the truck was REALLY bouncing around for long periods. But driving around logging roads shouldn't lead to coolant splashing out IMO, yet it does in my case. i'd expect everyone to have the same issues if it was a design flaw.

"Leaks" always look worse than they are, but sure enough, eventually I end up low on coolant.

 

[Mastiff]

Ancient thread. Ever get to the bottom of it? My 83 overflow just has a snap down cap, plus a little downspout that would allow overflow from the overflow. Bouncing around this weekend I saw small amounts of coolant down on the leaf spring and rad support. The overflow was nowhere near full.

 

[dyeager535]

I was having issues with losing coolant that weren't related to the cap. So I replaced the motor.

I did have some gasket material laying around, so I made a new one. It seems to have helped a bit, but since I'm now not losing coolant, my overflow has hardly any coolant in it, and while I noticed a tiny bit of coolant on the fender that I'm sure sloshed out, it's much less than before. I noticed the "sealing" surface on the overflow bottle didn't appear real flat, so I sanded that a bit.

The snap cap probably won't seal very well regardless, compared to the threaded cap style. But running a minimum amount of excess coolant seems to be the key.

 

[bp71k5]

My overflow was losing a little bit out the tube instead of the cap but has since stopped. I think the overflow level might have been a bit too high and sloshing coolant might just have been the cause. You have to really pay attention to the marks on the overflow/recovery tank.

 

[Mastiff]

Yeah, the overflow on mine is junk. The shape is kind of unique, not sure if I could find a replacement that would fit properly. Sounds like the newer factory overflows are threaded? Anyone know if they will fit older trucks?

 

[dyeager535]

Yeah, the overflow on mine is junk. The shape is kind of unique, not sure if I could find a replacement that would fit properly. Sounds like the newer factory overflows are threaded? Anyone know if they will fit older trucks?

They fit on the passenger fender, I *think* they bolt to the outer fender? Behind (towards back of truck) the battery. You might look and see if you have threaded holes in that area.

 

[Mastiff]

I'll check. Mine is passenger side right next to radiator down low under the battery tray, so it sounds like they moved.

 

[dyeager535]

I'll check. Mine is passenger side right next to radiator down low under the battery tray, so it sounds like they moved.

Yes, the earlier ones were like you described, later went up high. To me the later style seems more out of the way, probably because I mess around with the radiator/engine more than I do the overflow.