In all likelyhood it is the lower intake manifold gaskets...

 

160k miles id say its time for new intake gaskets anyways...especially since it sounds like the problem. how cheap did you get the truck for?

 

I got it for 1500. It was not the best deal, but i figured the black leather interior being basically new looking is worth that. It has new uniroyal gts tires, brakes (pads and rotors). I have will get all remotes and keys. Never been wrecked.

 

got around to pressure washing the eng off today. I checked the oil/water mix and noticed it was half way up the dip stick. So i said I need to pull the drain plug. plug the drain plug and after 1 hour or so it has overflowed my 16qt drain pan. i am glad i did not try to crank it. I did find teh rad had sludge in it, so maybe the cooler in rad is leaking.

 

i have had intake gaskets leak into the lifter valley causing the same situation as what you described.

 

Thats what i am hoping.

I am puttin new oil in and changing the filter and going to crank it to see how she runs. If the bottom end is knocking it will get a new to it engine. If she runs good with no knocking. the intake will come off to take a look. I am hoping for the intake gaskets. i will post pics soon.

 

changed oil. engine cranked, it does have some slight white smoke out the exhaust, but engine had good oil pressure and when checking oil after it had just a little water/sludge in it. I am gonna try and isolate if headgaskets are blown or not. I am still hopin for just intake being blown. It does idle pretty smooth tho.

 

The lower intake manifold gaskets are probably the biggest killer of these engines.

This is what I would do:
*Do not ever do a high pressure coolant flush on a 4.3.
I pull the thermostat and put a flushing Tee in the heater hose.
connect the garden hose to the tee.
Plug up the line going to the stat that you removed.
Turn the hose on and leave it for an hour or two. Turning it off and on quickly from time to time.

After the block is washed out. I'd plug up the stat. open the other end and repeat the flushing.
Get all that coolant out. Water leaking into the crankcase is nothing compared to coolant, and should give you time to test.

Good luck

 

got around to pulling the plugs. I see no evidence of it burning coolant. they are worn out, but look good.

Started removing stuff to pull intake and found the frt corners of intake leaking coolant like a water fall. the junk in the rad is stop leak. So hopefully i will get the intake pulled this weekend to verify the situation.

So far I need a rad, t-stat, plugs/wires/rotor/cap, intake gaskets, gonna replace valve cover gaskets while I am there and another oil change. I am hoping to have less than 2k in the blazer when done.

 

removed intake tonite to find the frt cooling ports to basically not have a gasket. they were completely gone. i pulled the pieces out of the valley. The only thing I didn't like was the lifter valley is alittle rusty and full of oil/water mix. I guess i will be cleaning it with diesel fuel.

Another intake gasket failure on a 4.3.

 

I bought my 1998 S10 with 34,000 original miles on it 3 weeks ago and the very next day it wouldn't start. So I take it back to the dealer I bought it from and they said I had a leaking intake.
They replaced the intake etc. then the truck wouldn't go when you stepped on the gas....So they change the fuel pump and they tell me I have bad gas..?? I put in new gas same problem....
So I take it back the next day again.... Now they conclude the water caused so much engine damage that they are completely rebuilding the bottom end.

Thankfully they are paying for everything.....with a 12month 12,000 mile warranty to boot.

 

damn that pretty good.

thats the only thing i am worried about. is it has set up for 3 or so mths with water in the oil. there is light rust on the cam and lifter valley. only time will tell.