Coolant Loss?

[TNGOP]

I have a 1996 1500 6.5L pickup and have been chasing the cause of coolant problems.

About 10 days ago, i replaced water pump b/c coolant was leaking out weep hole. Replaced it w/ 1997 series pump and dual thermostats to try to keep the engine cool, (although at no time has the truck actually overheated), I just know that keeping these engines cool is their life line.

Since water pump relacement, I drove around town with no overheating issues. However, one recent evening the low coolant light came on, I tried adding and heard the coolant pouring out on the driveway, (it was dark so left it until the morning). Next day, I checked the reservoir, hoses and ran a pressure test. No leaks, held 17lbs pressure, no crack in reservoir.... however, whenever the truck gets up to temp., it begins to leak antifreeze out the overflow until the low coolant light appears. Am looking for advice and am hoping its not the cracked cylinder head death toll. Anyone have a suggestion? Thanks in advance!

[Stumped]

I am not at the shop right now,but doesnt it have an air bleed on the later model t stat housings?Possible that air may be trapped in the system?I was thinking there was a bleed right near top hose.Nashville.....bought the best car ever owned in life there,sold it last spring.18 yrs of loyal,gas swilling service.That old car got me thru the partyin days(Kingston Springs Tn,Nolensville Jam) 2 wives and a kid.....

[Stumped]

the guy that bought it put several thousand $$ in it.Looks brand new now.Even had orig color put back on carb.Bet NO amt of $$ would get the ex wifes looking good again...

[TNGOP]

Thanks for the advice, and yes, there is a valve on top of the T/stat housing. However, when I'm at my best I am only a novice mechanic, so I have to ask: in order to attempt to bleed the air off, should I do so while running, while hot, while cold, w/ radiator cap on or off? Does any of that matter? Thanks!

Also, what kind of car did you buy in Nashville?

[grancito]

The quickest way is to open the valve, engine not running and squeeze the top radiator hose, the air comes out, shut the valve and let go of the hose. It will suck coolant from the resevoir, repeat till coolant comes out. Engine cold,so not to burn your hand and pressure cap off.

[Stumped]

69 Cutlass Supreme 350 rocket 310 horse 390 foot lbs at like 2300 rpm.Boy that old girl ran good,but swilled fuel.I honestly dont know what the procedure in the manual says,but I would do it running and right after t stat opens.You should be able to put your hand on the housing and feel the temp change,crack the bleeder with cap on.Be careful as liquid may squirt out.I hope others may chime in for procedure.Is oil milky or anything like that?I was wondering if excess pressure may be what caused water pump to seep to begin with.I hope its not a head or gskt.Its not a little job,and parts will need to be inspected very closely.By the way,make sure nose of truck is highest point during bleed procedure(not facing down driveway ect) not trying to be a smart a__ with that suggestion,but you want air to travel up and out.If you do need a mech,make sure to get a diesel mech(GM dont have any for the most part) it may be a few more $$ per hour,but poor work can kill our diesels.

[Stumped]

Actually,I like Grancitos method better.No chance on getting burned.Keep us posted so we can all learn

[TNGOP]

Will do. it will be tomorrow b/c its Football Time in Tennessee! Thanks again for everyone's advice!

[TNGOP]

Well- vols aren't looking good, so I thought I'd come back and agree with your opinion of the 69 cutlass. I'm also a muscle car guy, and know the 455 w-30s are not easy to overcome. Know its all debatable, but suspect it takes an LS6 or 429 to pick on that 455.

Again- thanks for the tips on bleeding air. I wouldn't have thought to park the nose uphill, so comments aren't taken as being a smart a$$. Don't know that I've mentioned, but I've already replaced radiator cap, looked for oil or bubbles in reservoir and haven't detected anything out of ordinary. Will bleed air tomorrow PM and report back!

[Stumped]

We raced a 70 w-30 in school.4:56s and an Muncie.Couldnt keep the 12 bolts together back then(79-80) could just go to any field and get parts(we had really big olds and chevy dealer here) now a 12 bolt brings $1000 in good shape.

[TNGOP]

So far, seems as though air in the system may have been cause of cooling system purging antifreeze. Planning on driving around a bit later to see how she reacts, but thus far, all is quiet in the coolant reservoir. Additionally, no white smoke, harsh starts or other signs of cylinders full of coolant, (thank God)!

As for Olds 455s, has anyone ever heard of a version of the W-30 with a black box as a part of the transmission with a label "eXpiremental?" The label on it was literally lowercase w/ X capitalized. Reason I ask is b/c a buddy of mine owned an eXpirimental 455 Olds, (I've seen photos of the car), but have never set eyes upon it personally. He purchased the car wanting a muscle car in mid-1980's, but wasn't a mechanic and was only mildly interested in going fast. He's not the type that would fabricate the description of the black box or eXpiremental label, as he would have no reason to do so. He didn't race the car, except on street and swears that he used to be able to punish LS6 Chevelles, 440 T/A cars, GTOs, other W-30s, etc. I've never heard of any limited number production vehicles directly from Olds, or of the lable eXpiremental, but thought I'd toss it out for anyone else to educate. Based upon his trustworthy description of this setup, it seems as though he was among the elite of the street. Eventually the 455 gave up and he sold the car. Howver, again, I'd love to know details about how this car was setup. Anyone know anything?