Yup.... still having the same problem. FMLLLLLL

 

I was convinced the issue in the video wasn't my problem until I got so feed up pouring coolant in that I finally pulled the valve covers, pressurized the system, and checked. My original 317 heads went to the recycler.

 

Another update:

I pressure tested my system again last night and it held 18psi for 25 minutes.

 

So you were losing pressure, and just couldn't figure out where it was going until you pulled the valve cover? I ask you specifically becuase I'm out of other options. I updated in the post above this. I don't lost pressure.

 

Re-tested the cap and it also holds 18psi for 25 minutes.

I'm stumped.

 

I was sure you had this resolved. Based on the images of visible coolant up at the front of the motor are you sure it isn't coming from the steam crossover or perhaps one of the freeze plugs in the cylinder heads?

 

Overtightening the thermostat housing bolts and warping the housing? Doesn’t take much.

 

Yes, I am sure because now when I pressurize the system it doesn't lose any pressure nor does it leak anywhere. I can also add that all the crossovers have brand new gaskets.

I'm SO CLOSE to pulling the heads to look. I've had enough .... with the Procharger setup going in this winter, i need peace of mind before winter hits. This needs to be solved. I'm also going to run the LS9 GM MLS gaskets. They are a little thicker and a favorite amongst the boost crowd. I'm also going to coat them in copper.

 

Did You ever put a new cap on as used rad caps build up muck in the area where the coolant goes back into the rad as it cools that is provided there is'nt muck in the cap ?

 

Seems like the issue starts once you have heat and pressure built up. Wouldn't hurt to get out the bore scope to see if you have any presitine looking pistons. I would think if you were leaking coolant into the crankcase or the cylinders you'd already know by now though.

 

The OG cap and this new cap both have yielded the same result and this cap does hold pressure.

 

That's where I'm at right now. I thought about inspecting the plugs too. I just dont know anymore. I'm frustrated.

 

I ordered a new AC Delco OEM radiator cap and new upper and lower radiator hoses. The hoses are the originals so I figured may as well since new ones are cheap... I don't expect this to make any difference.

I ordered new LS9 MLS gaskets as well.. hope it doesn't get to that but other than the radiator there's really nothing else it can be anymore other than some type of head/gasket issue.

 

After speaking with a couple reputable engine builders each of them said its very unlikely to be a head gasket issue.. this isn't surprising. They said it's not impossible but extremely unlikely as there would be other signs of issues.

Going to do some heavy diagnosing in the coming days before tearing it apart.

1 thing I noticed, is that out of all the times I've taken the radiator cap off, only 1 time did it gurgle and release pressure and it just happened after doing all the above work. However, the most recent time nothing happened at all and it was still pretty warm... maybe it is the cap/filler neck not sealing completely. Or maybe the radiator cap just isn't working properly even though it's holding pressure. Hoping the OEM cap takes care of it. One thing I noticed is that this cap design goes deeper into the filler neck than the original and the dimensions differ. Who knows... guess we will find out.

 

1 more thing before I dive into this... it seems as though I lose the exact same amount out of the radiator every single time. If that's true, it could be the radiator. It seems like I'm always adding the exact same amount either back from the expansion tank or from a bottle of new. I refuse to pull the expansion tank every time lol.

 

Just for fun last night I pressure tested the system and it lost just under 1 psi over the course of 12.5 hours.

Today I installed brand new upper radiator hose, lower radiator hose, thermostat housing, thermostat, coolant bypass hose, and a brand new OEM radiator cap. I brought the expansion tank down to the cold level. Replaced all coolant and bled from the crossover tube 4 times just to be 100% sure. Drove the car around town for 20 minutes. Parked it for about 1.5 hrs and checked the radiator level.

Problem still exists. Radiator was 4" too low or so.

 

Sorry to hear this, I know how frustrating stubborn issues like this can be. Sometimes you just want to drive the car into a swimming pool. LOL.

So is the excess coolant still getting pushed into the expansion tank? Or just disappearing now? Any extra amount in the expansion tank might not correspond exactly to the amount lost on this occasion since you just replaced all the coolant (in my experience, after a drain/refill, it's just not possible to bleed every last bit of air from the system without a full warm up/cool down cycle).

If coolant is being lost (meaning some amount more than what you're finding in the expansion tank), it wouldn't hurt to consider getting an oil analysis performed - especially before considering all the work of a head gasket swap. Any trace amounts of coolant in the oil should be exposed by this test. Also, a test of the coolant for combustion byproducts could be done. It would just suck to start tearing into the engine if there's no evidence of an internal problem; even if ALL the lost coolant isn't in the expansion tank that's still no guaranty that some amount isn't being pushed out (rather than in) when the engine is hot (but then the question of "where" still remains).

I've had radiator and heater core leaks that seem to only show up during specific points of engine temperature (or cool down). Assuming your pressure test was done cold, it might not have captured the window of occurrence. Something like that might account for the loss of system vacuum (in terms of not pulling coolant back from the expansion tank) as well as any additional/overall loss of coolant in general.

 

Excellent reply and greatly appreciated.

The expansion tank only rose about a half inch on the dipstick, but the radiator was low by 4-5 inches (it ALWAYS seems to be the exact same amout). This tells me it's not just a vacuum related issue and that I'm clearly having coolant disappear and right now it's disappearing fast. My drive was strictly in town and only last about 15 minutes. While idling in my driveway for about 15 minutes first. No coolant loss was observed during idling with the cap off.

My pressure tests have been done cold. Perhaps it's worth trying it hot but at minimum I think I need to look really really hard when the car is running and maybe even have someone bring the rpms up off and on while I do my investigation.

I do think it's time to send in an oil sample and see what it says. I did a combustion test a couple months ago and it was negative for exhaust gasses. I have the test kit sitting out and will re-do the test first thing tomorrow.

And finally yes, I'm pretty fed up lol.

 

Sorry, I just noticed back on post #1 that you mentioned doing the combustion test, but if the problem now seems worse then it certainly wouldn't hurt to try again. Plus the oil analysis to cover that base as well.

Definitely worth a check since other repairs and diagnostics haven't revealed the problem yet. I also noticed this other reply earlier in the thread:

I know the water pump isn't your issue (any more) but, as mentioned above, I've had both heater core and radiator leaks that seemed to hide or disappear except at full temp (or sometimes only appear during cool down). Harder to spot on modern cars with more junk in the way. On my Nova, the heater core leak was mostly on the engine bay side of the heater box and seemed to dribble down near the passenger side header collector (finally found the coolant trail one day when I pulled over to inspect it during a drive). I don't recall seeing any "smoke" exactly but I don't recall having any puddles when parked either, so I suspect it was either burning off on the header while driving (did occasionally catch a whiff) and/or dripping to the ground while moving but not leaking at idle speeds.

I do hope you find it soon, continually fighting with issues like these over long periods really sucks.

 

A second combustion check on the radiator yielded a negative result for exhaust gasses and remained blue.

I pressurized my system last night just to verify there were no issues with all the work I performed. This morning it had lost about 5psi with no visible puddles.

I did have a lot of smoke out of the exhaust this morning starting up, 60 degrees outside temp. Even after idling and checking for issues for about 20 min and a 20-30 minute drive, I was seeing puffs of smoke from the exhaust as well as quite a bit of moisture. I can't really tell if this was normal or not.