cooling problems

35xj

Well-Known Member
Joined
Aug 29, 2005
Location
Asheville NC
workin on the buggy again....
installed new fan. trying to bleed radiator (regular front mount)

trying to make sure i'm not just dumb. so.....


fill radiator leave cap off. start buggy. allow buggy to run, burp out bubbles.
buggy reaches 200 or so and begins to violently expell fluid from the radiator. (no fan running) elieve it has a 195 thermostat in it
it is my understanding that 210 is not overheating, so whats up? Buggy (with cap on does pretty much the same thing, but steams from the cap/overflow bottle at same temp)
fill cap is above motor. buggy is parked on small incline to place fill cap even higher.


WTF?
 
99 chevy 4.3 need to replace the t-stat. tomorow. if its a headgasket it just happened while it was sittin in the basement.
oil looks good, no water is obvious
 
35xj said:
99 chevy 4.3 need to replace the t-stat. tomorow. if its a headgasket it just happened while it was sittin in the basement.
oil looks good, no water is obvious
Click to expand...

Sounds like the t-stat is the problem to me and is also a cheep place to start
 
My vote is blown head gasket, or, cracked head. When it's bubbling as you described, and no water present in the oil or oil in water, what I would think it's doing is pumping part of the compression into the water system. Whis is why you get the bubbling at that temperature.

Or? your temp gage isn't acurate.

Massive over heating or, what I said at the begining is the only time I have seen one bubble like that.
 
new thermostat, same problem. it should be able to run with no cap, right?
it continues to blow water out the cap at 2-210. would a compression check show a cracked head?

any thoughts on how to get the air out?
 
Dumb thoughts.

1) It's not possible that you routed the hoses to the radiator backwards is it?
2) Is the fill cap the highest point in the system? If it's not it's troublesome to get all the air out.
3) Would prefilling the hoses with coolant make a difference in getting the air out? (I'm stuck on the idea that there is air in the system.)
4) Does the pump seem to be working? Is it possible that you routed the belt to it wrong?

I just can't believe it's a cracked head, unless you store the buggy is a freezer.
 
hoses are correct. water is flowing through rad. pump routing is correct.
pulled oil from the pan. no obvious water in it. gonna run compression test tommorow.
 
Water does not have to be in the oil for a head gasket to be blown, a crack in the head is usually what it is but not always, the compression can be leaking into the cooling system, not the cooling system leaking into the crankcase, usuallly you can see this out of the exhuast though as well. A compresion test will confirm if there is a mechanical problem to your cooling issue. If compression is leaking into cooling system a compresion test will show that compression is leaking not wear, a better way to figure it out is a leak down test. Pressurize the cylinders and find out if there is a compresion leak. valves have to be closed either oll the motor to TDC on each valve or pull the rockers. provided everything is sound and there is a crack in the head somewhere the air will fill the cooling system and depending on how bad the crack is will violently come out of the radiator.

Although not common on american motors, crappy european imports like to run plastic water pump blades splined to metal, the metal strips the plastic so the water pump blades will not be turning, if this is the case then b/c the water is not circulating you can't get the air out and as it heats it just expands to the surface. To check this pull rad hose to water pump or whatever take belt off stick something in there like long screw driver coat hanger and see if blades on pump are actually turning.

Also if compression is leaking into cooling system with cap on upper rad hose will immediatly get hard.

Another way although not helpful to you but if you had access to a sniffer you can sniff the coolant overflow bottle for hydrocarbons, shop around the corner has an old isnpection machine w/ sniffer, this is how I diagnose all my head gaskets requires very little work.
 
^
As always, Chase brings the good tech! I always enjoy reading his posts and usually learn something :) Thanks for sharing your knowledge, Chase!
 
Pirate talk:
blah blah hardcore,blah blah double shear, blah blah a million posts makes me all knowing. what's amatter didn't want to ask the brain trust over there Dave. :flipoff2:
Seriously how many times you ran that thing hot on the trail? Sounds like a cracked head, better check compression. On the slim chance you screwed yourself when you redid the front of your frame you should park it nose up on the hill into your back yard with the cap off and see if by some slim chance you got a air pocket in the cross flow in the heads/intake. Your rad does sit really low in it. What mix you running in it anyways, sometimes that can throw it out, oh yeah from Jody Bob :fuck-you:
 
35xj said:
new thermostat, same problem. it should be able to run with no cap, right?
it continues to blow water out the cap at 2-210. would a compression check show a cracked head?
any thoughts on how to get the air out?
Click to expand...



So one of the main points of the cap is to hold in pressure, which allows the antifreeze to have a much higher boiling point temperature than if it were exposed to atmospheric pressure.

What does it do with the cap on? maybe I missed that somewhere. The fluid will boil at a lower temperature with the cap removed.

Just a thought. I would expect antifreeze/water mixture to boil not too much higher than 210 except when properly under pressure in the cooling system.
 
so, when the t stat opens, and allows the fluid to flow, it spills out the cap opening? this is done at idle?
Try doing the same thing but with rpm's @ 1500-1800. It should make the waterpump suck the fluid down faster.
 
Talked to dave today...cracked head.
 
heads were not cracked. so after a valve job, decking.... couple other things its back together with new gaskets and appears to be fixed!
 
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