wierd cooling system problem noise ?

[sweetk30]

ordered the pump for a 1990 k5 blazer with 350/5.7 v8 . there full serp belt .

and unless i want to pop the back cover and check the impeller blade and trash the gasket i am at the mercy of the guy who boxed it .

[The Rocknrod]

I know what i'd do.

[andyh1956]

So the text of the GM tutorial is to plumb the cooling system like a BB or a Ford.
Strange that in the text of the 350 HO engine on sheet 2 while talking cyl heads it says " The water passages are the same as the original 1955 small block design."
Then on sheet 4 "Any small block engine, regardless of year, that uses Vortec heads, will require an external coolant bypass line from the intake manifold to the 5/8" hose nipple on the water pump (passenger’s side). Suggested routing is from the 3/8 NPSF boss on intake manifold to the water pump."
Go figure.
Anyway I have a 350 Ramjet down in the shop with a std rotation long water pump on it sitting on a motor stand. It uses Vortec heads. In the morning I will go look at it & see if it has bypassed cooling & report back.

[Captainfab]

I think what they are meaning is that the L31 Vortec heads do have the same coolant passages as the '55-'95 heads with the exception of the thermostat bypass hole. Thus the need for an external bypass. I brought this up here on this forum nearly 6 years ago and the general consensus was that it did not matter as long as a heater core was plumbed into the cooling system.

Originally Posted by andyh1956

So the text of the GM tutorial is to plumb the cooling system like a BB or a Ford.
Strange that in the text of the 350 HO engine on sheet 2 while talking cyl heads it says " The water passages are the same as the original 1955 small block design."
Then on sheet 4 "Any small block engine, regardless of year, that uses Vortec heads, will require an external coolant bypass line from the intake manifold to the 5/8" hose nipple on the water pump (passenger’s side). Suggested routing is from the 3/8 NPSF boss on intake manifold to the water pump."
Go figure.
Anyway I have a 350 Ramjet down in the shop with a std rotation long water pump on it sitting on a motor stand. It uses Vortec heads. In the morning I will go look at it & see if it has bypassed cooling & report back.

[sweetk30]

so the local parts store is getting me another water pump and doing a defective return . figure if i am going to pull it to check stuff might as well swap it under warranty . . . .

also going to add in the bypass hose like a bbc or sbf engine would have to help mimic the vortec flow setup . i got a napa 7296 molded rubber hose the fitment list is MASSIVE to say the least . . . its a 5/8" id hose both ends and a big radius molded 90* hose . so it should give me just what i need to work with on this one .

i have barb fittings already to use in this so we should be good to go . i am going to leave the 195* t-stat in for now and also flip the heater core flow back around to the orignal since i cant be hooking both to the water pump now and expect full suction flow from the intake .

[andyh1956]

OK I looked at my engine & it does NOT have a bypass hose on it. Also in the CPP catalog the photos of the 350 Ramjet do not show a hose.
I wonder if the '96-'99 5.7 Vortec engines have this hose?
It's interesting to note on all my race engines I have always tapped & plugged that hole in the block but I didn't run thermostats, only restrictor discs.
But I can see why with the hole missing in the Vortec head it in theory should need the bypass to keep the pump from cavitating before the thermostat opens.
PS- I wonder if the hole can be drilled into the deck of the Vortec heads?

[andyh1956]

Originally Posted by Captainfab

I think what they are meaning is that the L31 Vortec heads do have the same coolant passages as the '55-'95 heads with the exception of the thermostat bypass hole. Thus the need for an external bypass. I brought this up here on this forum nearly 6 years ago and the general consensus was that it did not matter as long as a heater core was plumbed into the cooling system.

I agree IF the heater core is constant flow & doesn't use an on / off valve in the hot hose from the manifold.
I remember having to change the hot water control valve on the boss's 99 Burb, it had four hoses on it & that coulda been to provide bypass cooling when the heater was turned off. But it was also a rear air / heat truck also w/ gobs of plumbing for that.

[Captainfab]

I would think that if a std rotation pump was used with a serpentine drive, there would be some serious over heating. More so than what is happening here.

[The Rocknrod]

Has anyone considered using a heater bypass valve in they're hose system?

[sweetk30]

guy on another site found this and linked it for me .

https://www.thirdgen.org/forums/cool...ing-issue.html

[sweetk30]

well i rigged up a test fitting today .

the 3/8" pipe thread port in the front of the vortec intake from edelbrock is for a bypass hose port if your using a vortec pump and i am NOT .

so i took the 1/2" pipe to 3/4" barb fitting out of the water pump today and swapped it for a 1/2" pipe to 5/8" barb fitting . then i used a 3/8" pipe to 3/8" brass compression fitting 90* to go in the intake bypass port hole . then a 5/8" molded 90* bypass hose was used from napa #7296 to link them together .

i did find a fitting on line thats going to make the hook up a lot better and more snug a fit on the hose for the intake end and help the bend over angle of the hose to keep it from closing off . reason is the water pump port is angled up 45* ish and over to the pass side . the intake manifold port is straight out the front and to the left of the water pump port location .

here is a few pics of the hose and fitting i will order and use when i do some other swapping around soon and have the system drained . https://www.ebay.com/itm/5-8-HOSE-B....l/191761802124

the hose size or fitting size do not matter to much as the intake has a smaller hole back in before it goes in to the crossover just below the t-stat location . so it only pulls the fluid volume it needs and its the same basic size as the older blocks and water pumps bypass port on the mounting face at the block on the pass side . here is the rpm edelbrock vortec pattern intake front drawing view . note the pipe thread port location bigger hose and closer to center . the smaller hole is for mounting brackets to it .

i warmed the truck up to mid 140* range and capped the rad off / topped off the over flow bottle and took her for a road test for almost 20 min driving . 30-50mph ranges and not 1 burp / girggle / sound from the system . got the tinyest wiff of coolant smell early on was all and nothing after the fact . temp gauge was a lot more steady and didn't do as big a swings from open to cold . so cross my fingers i think its 99% solved but not sure until more road time .

[andyh1956]

This has me wondering if those Dart heads I traded a rifle for last year have the by pass hole in them???

[The Rocknrod]

So when you get this up and running are you going to post a pic of your bypass hose setup?

[sweetk30]

i can post now . but its just like a bbc bypass setup only a sbc .

this pic is of my crude test combo . i ordered both a 90* and the 45* fitting to help make the hose angle better with the best option .

[andyh1956]

I don't have one handy to look at but does the '96-'99 5.7 Vortecs have this by pass factory installed?

[sweetk30]

yes its part of the 96-03 vortec 5.0/5.7 water pump system .

this problem is more for us guys using newer motor in older vehicle and older drive bracket system .

[sweetk30]

so i did a bunch of driving around town today and its cold out so she got cooled off a few times and had to warm back up also .

happy to say zero smell in cab / more stable temp gauge / no sounds of the burping - girggling from the rad cap .

[garyd1961]

On a non-AC truck all you need is a heater core "that's not clogged" plumbed from your intake to the water pump you should be fine. If you don't have a heater just run a loop of hose from the intake to the water pump.

Although sweetK30's set up should work fine and probably what you need if you are running AC.

[sweetk30]

garyd1961 i did try the heater core plumbing like you siad and GM them self said when i called them . it cut down 90% of the noise /smell but didnt NOT fix it for good .

so i plumbed it with the bypass hose as someone else did years ago on the link i posted and so far 20-30 miles in 2 days of driving we are good .

and the pics posted show why you need the bypass hose as the heads are not cast and setup for the flow like old .

[garyd1961]

Whatever works, I'm glad you got right. Your way should be really good for an AC truck with the cut-off valve in the line. Here is a picture of mine before I installed a new heater core and plumbed it in. It's still the same except now the water runs through the heater core and back to the pump.

[SunSoaked]

I got the same setup as k30. Vortec heads and serpentine drive. I never had any problems. This thread made me think so I did some investigating. The ONLY time I don't have flow thru the block/pump is when the thermostat is CLOSED AND the A/C is ON! That's because I have Vintage Air and it uses a heater block off valve that closes of the heater core when the AC is on. For that one rare occasion, I went ahead and installed a bypass hose (see pic). Kept it simple-less than $5 in parts. Problem solved.

[sweetk30]

sun soaked . . . same rpm intake and arp bolts no less and temp sender in the bypass port .

i guess i am the unlucky guy the first 2 didnt work good and it needed the bypass port direct to the intake .

[SunSoaked]

Originally Posted by sweetk30

sun soaked . . . same rpm intake and arp bolts no less and temp sender in the bypass port .

i guess i am the unlucky guy the first 2 didnt work good and it needed the bypass port direct to the intake .

I'll say it again... those hubcaps are bad luck. Take them off and send to me.

[The Rocknrod]

Check out this bypass pic from a 65 with a V8 board member cru_zn_29 owns:

[sweetk30]

nice pic .

i got my 90* and 45* barb fittings the other day . when my new intake shows up and gets installed i will post a few pics of the cleaner install and new intake setup i picked to feed the truck .