Hello everyone, I'm new to all this .
I have a 91' Blazer and it's been drinking coolant for awhile now, about a gallon in the last 3 1/2 months..
There is no oil in the radiator and no water in the oil and no coolant hits the ground.
And at cold idle runs perfect, warm idle runs a little rough and doesn't seem to be firing on #1 cyl, which makes me fail the emissions test.
warm running down the road runs great and also passes emissions with flying colors.
TBI Injection is producing excellent fan patterns no drips.
Egr holds a vacuum and engine idle go's goofy when i depress the diaphram.

So my question is this could the crossover on the water jacket going from 1 bank to the other be leaking into #1 cyl some how through the intake manifold?

Looking forward to your input

 

Is this a K5 Blazer?? or a 5.7L swap??

If you are not noticing coolant on the ground and you cant trace it any where i bet its time to replace intake gaskets. I know that the engines aren't the same but my 3.8 was leaking coolant but couldnt see any leaks. And had rough idle at low temps but once headed up it went away. The 3800 series had big problems with this but this can happen to any engine. [Normally it will have rust like stuff in the radiator] NVM this but i did not have any oil loss or water in it.

It also could be head gaskets but most of the time you can see them leak.

Have you been replacing it with Dex-Cool coolant?? I hope you havent... This is what happens if you do and that was the good one. It is due to the Dexcool becoming acidic and eating the gasket. i know it didnt come standard until 96 but still could have had the coolant replaced and they put it in.

 

It looks exactly like my old 79' K5. the 5.7 L is a 350 cid. no Dex coolant i know of. i have used prestone and good old distilled water..
I think what i'm going to do is tear off the carb , kit it ,, take off the intake and see if i can see any place water may be getting through.
I hear permatex Gray is the best sealant, what do you guys think ?
I'm also going to try and get the valve covers to stop leaking, driving me nuts, passenger side bank always leaks even with rubber gaskets, so this time i'm gluing them on.

Thanks for the post Brute

 

Np and they moved it to the K5 section, it was in the 1st gen S10 Blazer section and thats why i was confused. and ether red or gray as long as its permatex. Red is more for coolant and gray is more versatile but it should not be that big of an issue

 

Grey it is , Thank You

 

she's all better now

 

What fixed the problem?

 

I'd like like to know this as well, as I seem to be having the same problem with 90' K5 Blazer.

 

a gallon of water in 3-4 months isnt really alot depending on how much you drive. alot is usually when you see puddles. my 90 fullsize was kinda doing the same thing. kept slowly getting low with no leaks. ended up being the water pump. it just leaked when the truck was running and with the fan going it would just splatter it around so i never seen any spots

 

Always be mindful of the ole heat core also. Check for dampness on the carpet right under the dash on passenger side.