1994 Chevy Silveraldo 350 engine questions...

SHIFT664

New member
I had a morning that the t-stat got to going up and down between 230 - 290+. Changed the thermostat and filled with anti-freeze. 2 wks; later, Christmas eve same thing put a gallon and a half in it. Full as of now, wife said she smelled a-freeze and temp went to 230 or so today.

I went to pull the vlv cover to see whats going on and this is what I seen just by pulling the 4 bolts from vlv cover. The clean bolts are from the front and back cylinder area on driver side.

http://s543.photobucket.com/user/SHIFT664/media/IMG_20131230_182513_zps3e2db039.jpg.html?sort=3&o=0
http://i543.photobucket.com/albums/gg480/SHIFT664/IMG_20131230_182454_zpsca7b023d.jpg
http://s543.photobucket.com/user/SHIFT664/media/IMG_20131230_182442_zpsbf36d2f3.jpg.html?sort=3&o=2
http://s543.photobucket.com/user/SHIFT664/media/IMG_20131230_182428_zpsc670cac7.jpg.html?sort=3&o=3

Let me know what you think. I know the pics are dark.
 

Outrider

Member
don't look milky like water got in the oil.

It can work either way - look for oil spots floating around in the coolant, too; a leaking/blown head gasket blowing into a water passage between the head and the block can cause these symptoms, usually accompanied by a periodic loss of coolant as the cooling system is being (over) pressurized by the combustion process. Next time you fire it up, look for white smoke coming out of the exhaust pipe, white smoke that doesn't go away after the engine is thoroughly warmed up and has been running for a few minutes. With my truck it was easy to spot because the truck had factory duals (true duals, not a system forked behind the muffler) and one smoked and one didn't after it was warmed up.
 

SHIFT664

New member
Doesn't seem to smoke but I will check that. And I will take another pic today. those where just the bolts that hold the vlv cover down. 2 was ok and the other 2 was black sludge all over them.
 

flattop1

Dawg 89
don't think them bolts mean much cept not too frequent oil change and lotsa miles.
drain back holes could be pluged or pvc is on one side or the other.
How about your radiator overflow tank is it oily or full of slim/crud?
any issue starting after warm or sits for a while?
Does it miss when first started then clear up
all indicative of coolant leak into engine
if losing coolant it has to be going somewhere
small leaks are hard to see
Attwood says common for intake I would look there first.
 

SHIFT664

New member
don't think them bolts mean much cept not too frequent oil change and lotsa miles.
drain back holes could be pluged or pvc is on one side or the other.
How about your radiator overflow tank is it oily or full of slim/crud?
any issue starting after warm or sits for a while?
Does it miss when first started then clear up
all indicative of coolant leak into engine
if losing coolant it has to be going somewhere
small leaks are hard to see
Attwood says common for intake I would look there first.

overflow does look a little cruddy, maybe some sludge, and no issue starting cold or warm, does pretty good really. But it does seem to have a miss in it for a few minutes until its good and warm, Now I can barely hit the throttle going down neighbor hood street. and turning at stop sign on to main road it seems to miss when I have to get in the gas more heavily.
 

mopdog

Member
Pull the plugs and see if one looks washed out....sometimes easy to tell when one doesnt look like the others or the top of one piston is clean. Also can put pressure on the collant system and look in each cylinder....not easy sometimes but a good flashlight, mirror, or a scope will help.
Those motors are very well known for intake manifold coolant leaks, usually pools on top of the manifold and runs down the front or back. Ive seen alot of water pumps get changed when it was the intakes because of where it runs down the motor.
 

SHIFT664

New member
Pull the plugs and see if one looks washed out....sometimes easy to tell when one doesnt look like the others or the top of one piston is clean. Also can put pressure on the collant system and look in each cylinder....not easy sometimes but a good flashlight, mirror, or a scope will help.
Those motors are very well known for intake manifold coolant leaks, usually pools on top of the manifold and runs down the front or back. Ive seen alot of water pumps get changed when it was the intakes because of where it runs down the motor.
what do you mean washed out?
and here is the pic of the vlvs in the daylight with no fat thumb involved.
:)
http://i543.photobucket.com/albums/gg480/SHIFT664/IMG_20131231_161833_zps54de1133.jpg

I know I need new vlv cover gaskets, but not gonna do it until I know how far down I have to go.
 

flattop1

Dawg 89
that all looks fine would be all gooey like a milkshake if ya had water in the oil.
washed out he prolly means washed clean from water anti frezze. pull plugs and look for water in 1 or 2 94 has hei right pull plug wire while running to find miss pull that or those plugs. does it overheatquickley and blow out the overflow.
 
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