Coolant Expansion Tank

Charlie Chops 1940 · June 13, 2008, 07:52:50 PM

Ah, another rainy Friday night.

Last week at Indy I got the track roadster a tad warm (220f) in traffic on the way from registration to the campground. No big deal as it didn't have an eruption of any sort.

I picked up a small brass expansion tank ( early 60's Ford I suspect) in the swap meet on Friday thinking it might look better than my current catch can. Today I took out the 180f stat and installed a 160f unit in which I drilled six 1/8" holes around the flat part of the stat (this will frequently stop the spike in gauge reported temp just before the stat opens)

So when I remove the stat housing I find no water under it. And I also note that the stat and housing are higher than the radiator top tank. I knew this was the case but I just never applied any significance to it until today. Probably means I never had enough coolant in the system from the get-go.

Now comes the real purpose for the expansion (if that is the correct term) tank. If I mount it higher, or at least as high as the stat housing I should be able to fill the system through it. The e-tank has a radiator cap/fill neck with an overflow bib, another like sized bib at the other end of the tank and a 3/4" heater hose bib down low.

The 153 has a stat housing bolted to the front/top of the block just like a 230/250/292 Chevy 6. The housing has two threaded hole, 1 is for the temp sender and I'm using the other for the sensor to turn the electric fans on. Both are below the stat.

I'm thinking the 3/4" hose needs to go to one of the housing locations and the lone bib on the tank needs to complete the coolant loop from the radiator. Getting it at the radiator cap would be good but I can't figure out how to seal the radiator and get coolant to be present in that line under normal temps. Early Vettes had a similar alum. tank and just had a bib in the radiator top tank (no cap and bib on the radiator). The cap/bib arrangement on the e-tank would be fill and overflow.

I'm not to fired up about removing the rad. to modify it. Can I just remove the radiator cap pressure parts, re-install the cap, and thus complete the loop?

Now that I've put it down in writing it seems to make perfect sense. Does it pass the Enjenjo home brew solution?

Charlie

GPster · June 13, 2008, 08:57:43 PM

This late in the day you can word better questions than I can read. Is your motor one of the old Chevy II mills or is it an "Iron Duke" or is it an early motor with the cross-flo head. I read somewhere (maybe here) a dissertation by someone that seemed to know (Wayne, Skip, ?) about the crossflo heads and a short cycling water flow. I paid attention to this subject mainly because the Jeepster will have no use for a heater and as far as a defroster I'm thinking about just mounting a fan at the top of the windshield. Back in my old days if I didn't want a heater I'd just plug the fittings and get rid of all that extra hose and clamps. This talk got me to wondering and thinking there was a legitamit reason for the mass of hoses and the extra hose fitting on the radiator of the S15 that's under the Jeepster body. So I didn't plug any fittings and I just went out and checked, so here's what I think. The thermostat housing on the head of my 2.5L '87 engine is tapped for 2 fittings. One of the holes has a sender with 4 wires on it probably for the temperature gauge and computer input. The other hole has a 3/4" hose barb fitting in it . Because the cross-flo heads can't use the exhaust manifold to heat the intake manifold it looks like they do it with hot water. There was a hose off of the back of the engine's side that had the hose that went to the extra fitting in the radiator. All along I thought it came out of the water jacket in the head. It comes out of the back of the intake manifold. The hose that comes off of the thermostat housing goes into the front of the intake manifold. Now the talk that I remember did have a good reason for water short cycling the thermostat so I'd do what you said but that's where it went and what it did. GPster

Charlie Chops 1940 · June 13, 2008, 09:02:21 PM

It's a Chevy II engine Joe. Intake and exhaust are both on the driver's side which leaves room on the pass. side for for the expansion tank.

Charlie

enjenjo · June 13, 2008, 10:35:20 PM

It should work Charlie, but I'm not sure the seal on the top of the cap will be enough to seal it under pressure. If it doesn't, you can try some other caps.

Charlie Chops 1940 · June 13, 2008, 11:14:48 PM

The caps I've looked at have a rivet in the top that holds the pressure spring parts in the cap. If I drill that out & silver solder a patch on the water side and make a full gasket I suspect it won't leak under pressure. After all it does hold the coolant from leaking at the cap and directs the overheating water out the overflow bib when the spring retracts the inner seal.

Nothing ventured, nothing gained.

Charlie

Quote from: "enjenjo"It should work Charlie, but I'm not sure the seal on the top of the cap will be enough to seal it under pressure. If it doesn't, you can try some other caps.

slocrow · June 14, 2008, 08:54:37 AM

Charlie, I e-mailed you a larger version. Maybe it will offer some help or at least cause some more thinking.........Frank

Charlie Chops 1940 · June 19, 2008, 05:47:02 PM

So I finished the expansion tank installation today. I wasn't able to find a radiator cap without the pressure feature so I used a 7# unit and removed the gasket and the disc on the end of the spring that seats in the bottom of the neck. Left the spring assy in place. Now it just seals the neck and lets water flow from or to the expansion tank.

Took it out for a good 50 mile workout. never went over 175f and leaked nay drop. Crossed that one of the list.

Charlie

Dave · June 19, 2008, 05:56:43 PM

Not bad looking of a setup for an old guy...
Dave

Charlie Chops 1940 · June 19, 2008, 06:10:52 PM

Well, you know us old guys...we're already been over the top and going down the other side....

Charlie

Bruce Dorsi · June 19, 2008, 08:41:57 PM

I've been wondering how you made out with the Webers. All sorted out, yet?

Charlie Chops 1940 · June 19, 2008, 09:15:39 PM

Bruce - not all sorted out, but better. They are pretty good once the engine reaches a reasonable operating temp. Talking with a Weber tech guy determined that the most likely culprit for the bog was too lean on the idle circuit. So, I ordered a set of next size up and that is next on the to do list.

That stumble is right around 2000 rpm - you know, right where I wanna drive. 2000 in overdrive is 60 mph, so the way it is now I can't run 55 in OD. I may have to look at rear gearing change, 4.11/4.33's might be better than the 3.73's. Time will tell.

Charlie