New Engine - Exhaust in coolant...

[kris]

(I posted this on ifsja with little response. Hopefully we can figure this out here...)


Its a long story.
http://www.ifsja.org/forums/vb/showthread.php?t=72976

Heres the short...
Had hot running/overheating issues forever. Tried new radiators, clutches, water pumps, AutoMeter temp gauge, you name it. Got the NAPA block test kit, had exhaust in coolant. Pulled heads, had them checked, they checked out ok (but I wasnt convinced), used new FelPro gaskets and a new set of ARP bolts. Still had same issues.

Figured it was a cracked block so I pulled the old engine, got a known good core from a generous member on IFSJA, and built another engine.



I have 170 miles on this engine the temp gauge has started doing the same things. I went out today and (using a lever-vent cap) got all the "air" out of the radiator. I squeezed the top hose until there were no bubbles in the overflow.

Started it up with the lever open and let it get to operating temp. Once up to temp for a few minutes and varying the rpm's, I squeezed the hose and got bubbles in the overflow.

…I let it cool and got the NAPA block checker out…


Ive got bubbles bad. Fluid goes yellow/green in one squeeze of the bulb.

There is exhaust in the coolant.




I do have one question based on a part I reused from the old engine. The intake manifold.


Is there any way for exhaust to pass (by way of a crack or flaw) from the exhaust crossover/egr passages in the stock 2bbl intake manifold into the cooling system ?

I have an older stock 4bbl manifold I looked at, and it just doesn’t look possible… But you never know… Doesn’t hurt to ask…

k.

[jeepsr4ever]

Collant ports on intakes are in the front and back with an exhaust crossover in them middle. The only way to get exhaust into the coolant would have to be from the heads.

[kris]

Thats what Im afraid of.

Do these blocks crack ?
This was supposed to be a good (cool running) runner when I got it, it came out of a wagoneer that belonged to the father of the guy I got it from. I did not use my old engine...

I used FelPro's, squirted the backsides with KW coppercoat, ARP bolts torqued to 120lb/ft in sequence starting at 40lb/ft with 20lb/ft per pass.

Heads were mag checked 170 miles ago.

I have about 3k into this build, and I swore after the last one I wouldnt build another... I love AMC's, but when do I cut my losses ?


k.

[jeepsr4ever]

Cylinders are the most common crack on an AMC block but thats rare. About a third up from the bottom is where you can have a thin spot but you would see the cylinder filling up with coolant and the spark plug looking funky. It is also possible you have a warped head as well. Heads really arent that hard to change dont loose faith in the iron just yet you just need to put a little more time into it. Cylinder heads are abundant for a bridged rocker AMC!

[ironman_gq]

yep check for warped heads. you should be able to tell if the heads arent sealing right by looking for track marks on the gasket when you pull the heads.

[Grey Ghost]

before you tear the heads off remove all the rockers and pump compressor air into each cylinder and look for bubbles in the coolant.this could help give you an idea were the leak is.

[kris]

Warped heads within 200 miles of the rebuild when the deck was milled .020" and the heads resurfaced ?



I went out today and ran the test again but this time I let it stabilize for a while at operating temp. Bubbles wernt as bad as last time, probably because I wasnt getting expansion in the cooling system forcing air out while finishing the warm up.

So bubbles are less, almost non-existant at idle. With the A/C on (for some load) at about 2k, theres not much more but theres a rush of them when I let off the gas for a second or two, then back to almost non-existent...

Someone was telling me recently that its normal to have "some" combustion gas/residue in the cooling system. Personally I cant believe this, but have to ask...

Is it "normal" to have some detectable gas in the system ?

If not "normal", is there some acceptable amount as long as your cooling system can keep up with the extra heat load ?

With the NAPA "block tester" (apparently) being a PH tester, is there any way that something other than combustion gas in the cooling system is tainting the test ?


I guess Im still in denial about this. :-|

k.

[ironman_gq]

any residue left over from the block cleaning will throw off PH tests as well as the type of coolant and the age of the coolant used. most dip solutions are usually alkali for dissolving the grease and oil buildup in engines. Do you have any oil residue in your coolant or any coolant residue in your oil? do you smell coolant in the exhaust? If not you may just have a contaminated cooling system or having some point boiling going on in the engine or cavitation creating bubbles. Radiator flush may also throw off the PH test as well :sa:

[fifesjeep]

Warped heads within 200 miles of the rebuild when the deck was milled .020" and the heads resurfaced?

Were the heads bolted down properly etc...
If the shop used an old/warn-out machine when they machined your heads there's a good possibility that the surface is "wavy"... The High spots being the ends and the meat in between the chambers... the low spots being the edges where the chambers are located...

[AMX69PHATTY]

Any way to get ahold of a Coolant System Pressure Tester ? Don't know if Advanced or other parts places loan them out or not. They may have them at Harbor Freight. Just a hand pump with a gauge attached by a hose to a radiator cap. Attach cap to radiator, pump up pressure with the hand pump, watch pressure on gauge, let set a few hours or overnight maybe, see if system is still holding pressure. Would be one other way to help determine if the cooling system is properly sealed up.

[ironman_gq]

summit might have em otherwise try your local tech schools they usually have most of the equpment needed and are usually more than willing to help out. Some of the bigger ones may also have an automotive machine shop on hand and they usually dont charge a labor fee for work