A few questions

[tishjoh]

I have a 2001 S10 4.3L that had a coolent leak that I could not find. I have it torn down now to the block and noticed that the rear water jacket ports between the block and the head on both sides has a lot of corosion, but the other ports dont. Also when I took out the block coolent drain plug on the drivers side, nothing came out. I had to take a screwdriver and break out a bunch of corosion. Is this normal? I have read a lot on here about the coolent problems that others have had, but did not find anything about this.

Also when I pulled the heads I had 2 pistions that looked like they had some coorsion on them. Also anywhere the head gasket covers a port that has coolent in it, it has a lot of corrosion on it as well.

I checked the compression before the teardown and all was good so I do not suspect a head gasket. Am I wrong to assume this?

I have attached a couple of photos to show what is going on. Any thoughts would be appreciated

[nukem1st]

Dex-Cool strikes again.

[lucy_blue_93]

Dex-Cool strikes again.

X2!!!:D

[bespurcell]

X3

[Mikz86TA]

X4

[rat]

That is normal. The back ports have no coolant flow through them, so they tend to collect sediment and rust.

[SCredneck]

One question...not trying to hijack this thread, but wondering why do they block off the rear coolant ports with the intake gasket? Why put the coolant crossover in the rear of the manifold if coolant is not intended to flow thru there?

[rat]

A 2001 doesn't have a coolant crossover back there. And the coolant ports aren't blocked by the gasket.

I think the older engines took the coolant for the heater core back there though.

Unless you are talking about why they put them in the heads at all, and the reason for that is the heads are the same. If you were to put the heads on opposite sides the back coolant ports would be on the front and vise versa.

[Zygoat]

to answer the original, i think the head gasket is fine, sounds/looks like the lower intake gasket to me. good luck man!

[SCredneck]

A 2001 doesn't have a coolant crossover back there. And the coolant ports aren't blocked by the gasket.

I think the older engines took the coolant for the heater core back there though.

Unless you are talking about why they put them in the heads at all, and the reason for that is the heads are the same. If you were to put the heads on opposite sides the back coolant ports would be on the front and vise versa.
Rat,
Was asking particularly about my 95. Just changed intake manifold couple days ago. intake gaskets blocks off rear coolant ports, but there is a coolant crossover back there in the manifold and yes the heater hose comes off of that passage in the rear of the manifold. was just curious as to why they block off those rear ports with the gasket. Inquiring minds want to know, that's all.

[Zygoat]

if there is a crossover in the manifold and you heater hoses come out of in(hook in) in the back, then they gasket should not block the passage, that would be bad.

[SCredneck]

That's the way the originals were that came off, there was a metal plate made into the gasket blocking the rear coolant ports. The new gaskets also had the rear coolant ports blocked. Truck has never run hot except for the one time when the water pump gave up. Just has me curious, I'm the type that wants to the the "why" as much as the "how".

[Zygoat]

yea its interesting. if you know for sure that those were the stock gaskets that were on before than thats prolly how it was supposed to be, i dont know the motor u have really well, i had a tbi but its been a while and it was older than yours. so i am just going by what you said.

can you post a pic of the rear of the motor, where the heater core lines run?

[SCredneck]

Will try to post pic tomorrow. One heater hose connects to manifold above #6 cylinder. The other heater hose goes directly to the water pump. See the attached pic of the new gaskets. Notice the coolant ports, open on one end, blocked on the other. Where the port is blocked, the gasket is embossed "rear port do not remove".

[tishjoh]

Thanks for all the input and help in understanding this.

John

[Cameo_S10]

Very interesting.:D

[SCredneck]

Per the instruction sheet that came in the box with my new Fel-Pro intake gasket set:

IMPORTANT: Intake manifolds with a rear mounted heater hose connection must use gaskets with restricted rear coolant ports ONLY.

I'm just wondering why that is.

[rat]

So that your heater works...

[SCredneck]

OK...it's make the redneck feel dumb day.:D

[bespurcell]

LOL

[tishjoh]

Ok, someplace I was reading that if any of the dexcool got into the oil that I will need to replace the rod and main bearings. I cant seem to find that thread again.

Now is the time to do it as I have it all torn down to the block. Heads are gone. Also, is it worth my time to remove the bock and change the rear main seal while this far into it?

jt

[rat]

Ok, someplace I was reading that if any of the dexcool got into the oil that I will need to replace the rod and main bearings. I cant seem to find that thread again.

Now is the time to do it as I have it all torn down to the block. Heads are gone. Also, is it worth my time to remove the bock and change the rear main seal while this far into it?

jt

It isn't a dexcool thing, it is a coolant thing. You don't want water in your oil. Since oil floats on water and the oil pump pickups inlet is at the bottom of the oil pan if you get enough water in the oil you will be pumping water.

So, it is your call if you ran it with enough coolant in the oil to do the above.

[tishjoh]

Just a followup. I decided to pull the motor, looks like a good thing I did. When I pulled the main bearing caps off the oil was a milky white and some very uneaven wear on them. It looks like the crank is in good shape though.

It is off the the machine shop to get the block cleaned up and then start putting it back together.

One question I do have though, I am assuming that when they hot tank it, it will ruin the cam and balancer shaft bearings as well, is that correct?


Thanks for everyones help

John

[SCredneck]

If I had it torn down that far, I would just automatically replace ALL bearings and call it cheap insurance.