4.3L Cracked Block?
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4.3L Cracked Block? - 3/29/2008 8:52:30 PM
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Navy85
Posts: 15
Joined: 2/24/2008
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The Frustration-Meter is definitely pegged out.
Some of you may remember my posts from several weeks ago about dropping a bolt inside the engine with the intake manifold off. After removing the front axle and dropping the oil pan, I finally removed the bolt and proceeded to put the engine back together. I was feeling pretty good. This started as a job to change a blown head gasket.
When I turned the key yesterday, the engine turned over but wouldn't start. Determined that I hadn't put the distributor back in correctly, so I fixed that today. Started right up, but then...
Ran kind of rough for about 20-30 seconds and then the radiator overflow (just below the radiator cap) started spewing a light brown, oil-water mixture. Turned the engine off and drained the radiator...some water, some oil-water mixture. Figured I should drain the oil pan too, and got the same oil-water mixture.
Had the heads checked while they were off. No cracks. When I checked the old head gaskets, there was one small area on the gasket at the #2 cylinder that looked bad, so I assumed that was the culprit. I was very meticulous in putting all of the new gaskets in place.
Is it possible that I have a crack in the block that would allow the oil-water interaction? Would a compression test help diagnose the problem? Would very much appreciate any suggestions.
Thanks,
Steve
1996 Blazer, 4.3L 4WD
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RE: 4.3L Cracked Block? - 3/30/2008 11:45:22 AM
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Hanr3
Wheels & Tire Moderator
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I guess anything is possible. However the oil doesn't run into or around the piston chamber. Typicaly if the cylindar wall was cracked it would let the water from teh surrounding water jacket into the piston and out the tailpipe.
the oil does flow through the block in various places, so it is possible.
Did the gasket you installed block off the back two water jacket passages in the head/intake manifold? I know that isn't coming out right, and hopefully someone can clean up my English. maybe some pics will help..
Is this what your oil looks like?
Bottom of my Intake.
Notice the lack of water passage on the left side in the pic?
Now look at teh next pic, see the opening in the block and gasket for the water passage?
If you didn't get a good seal in the intake to head gasket your oil and water will mix.
At this point I would sya you need to verify your installation work before you go tossing the engine.
http://chevytruckworld.tenmagazines.com/gallery/Hanr2/245113.jpg
http://chevytruckworld.tenmagazines.com/gallery/Hanr2/245116.jpg
http://chevytruckworld.tenmagazines.com/gallery/Hanr2/245121.jpg
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"Some people spend an entire lifetime wondering if they made a difference.
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'87 S10-Blazer - SOLD
'93 S10-Blazer 4x4x4 - Sons DD, engine swap is done.
'00 S10-Blazer 4x4x4 - My
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RE: 4.3L Cracked Block? - 3/30/2008 12:48:26 PM
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Navy85
Posts: 15
Joined: 2/24/2008
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Good pictures. Thanks.
Yep, that's what my oil looks like. The intake manifold gaskets that I installed did not block the two rear water jacket passages. Now that you mention that, I do remember that the old gasket did have those areas blocked off. Sounds like I'm going to be pulling at least the intake manifold again, so I'll be sure to get the right ones this time. The others came in a FelPro head gasket set.
Would really be great if this fixes the problem. Thanks for your help.
Steve
1996 Blazer, 4.3L 4WD
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RE: 4.3L Cracked Block? - 3/30/2008 3:57:10 PM
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Hanr3
Wheels & Tire Moderator
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No big deal if oyu have the openings in the gasket or not, the big deal is if you completely surround the water passages with RTV to seal it in.
I poured fresh oil all over the engine once I had the intake off to wash the oil/water mix through the oil pan. Clean the crap out of the engine, get all that water out of there. If that water gets between a bearing and the crank or rod you will toast the bearing. Change your oil filter too. Once you get it all back togehter, run it just long enough to verify the leak is fixed, shut it off and change the oil and oil filter again. Drive it 50 miles or so on the new oil, and do another oil change. Then change it as needed.
Thos pics came from my '93 after I did an engine swap. I dropped in a '85 4.3L blcok into a '93. I had to drill one head accessory bolt and drilled too far. I put a how into the water jacket. My fix was WB Weld, and new gaskets. Plus the oil change routine. My son has been driving hte truck every day since for the past 1 1/2 years wihtout any trouble.
_____________________________
"Some people spend an entire lifetime wondering if they made a difference.
The Marines don't have that problem."
-President Ronald Reagan
'87 S10-Blazer - SOLD
'93 S10-Blazer 4x4x4 - Sons DD, engine swap is done.
'00 S10-Blazer 4x4x4 - My
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RE: 4.3L Cracked Block? - 4/16/2008 6:25:44 PM
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Navy85
Posts: 15
Joined: 2/24/2008
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Finally got a chance to get the engine put back together and was about to start it. Checked the dipstick and there was water on it. I didn't do too well in Chemistry, but I remembered that oil floats on water, so I drained the water out of the oil pan until oil started coming out. For all of the water that came out, the whole oil pan must've been full of water! Seems that when I was putting water in the radiator, it was ending up in the oil pan. All of this water got into the oil without the engine running.
The radiator level is only going down about 3 inches. Does this mean that the leak is high?
I refilled it a few times over several days, not thinking that there could be a leak somewhere.
When I put the intake manifold back on, I gave the water jacket passages a good layer of RTV, so I don't think that's the problem.
Any ideas?....Help!!!
Thanks,
Steve
1996 4.3L 4WD
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RE: 4.3L Cracked Block? - 4/18/2008 3:47:35 PM
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Navy85
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Here are my compression numbers...
#1 - 180 psi
#3 - 170
#5 - 175
#2 - 175
#4 - 190
#6 - 195
Based on what I've read, seems like these numbers indicate no head cracks and no head gasket issues. Correct?
#5 plug looked a little fouled but the cylinder pressure looks okay to me.
Still losing approx 3" of water from the top of the radiator.
Does this lead me back to the intake manifold gasket?
Any thoughts would be much appreciated.
Steve
1996 4.3L 4WD
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RE: 4.3L Cracked Block? - 4/18/2008 3:55:28 PM
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swartlkk
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From: Waterloo, NY
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Cylinder pressures look ok. They're all with in 10% of the average which is good.
Sure sounds like an intake manifold gasket leak to me. You could try a pressure test of the cooling system to see if you are getting coolant either into the oil or into the cylinders (you'd have to pull the plugs again.
How quickly does it leak down 3" from the radiator?
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RE: 4.3L Cracked Block? - 4/18/2008 4:10:05 PM
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Navy85
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The 3" goes down fairly quickly...no more than 5 minutes or so.
Could you please describe how to do a cooling system pressure test. My plugs are still pulled so no biggy on that piece of it.
Thanks,
Steve
1996 4.3L 4WD
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RE: 4.3L Cracked Block? - 4/18/2008 5:25:18 PM
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swartlkk
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From: Waterloo, NY
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Definitely sounds like something didn't get put back together right if you are loosing it that fast. At that point, a pressure test won't tell you much of anything other than you have a massive leak.
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RE: 4.3L Cracked Block? - 4/18/2008 6:02:23 PM
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Navy85
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Thanks, Kyle. Pretty much what I was thinking about the pressure test, too.
Besides the intake manifold gasket, is there anywhere else that the water would be coming from? Ruled out the heads and head gaskets with the compression test. Is a crack in the block possible? Or would that have shown up with the cylinder compression test? I don't have a problem disassembling the intake manifold again, but would just like to do any other necessary troubleshooting before I do if it could be something else.
Also wanted your opinion on intake manifold gaskets. I've been using rubber gaskets from Auto Zone, but I also have a $65 set of metal gaskets from the Chevy dealer. Should it make a difference which gaskets are used?
Thanks much,
Steve
1996 4.3L 4WD
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RE: 4.3L Cracked Block? - 4/18/2008 6:39:03 PM
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swartlkk
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Felpro makes the metal framed gaskets as well.
A cracked block is possible, but unlikely... really sounds like an intake manifold gasket problem. Seems like you are loosing coolant way too fast for a simple crack to a water jacket.
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Kyle-
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RE: 4.3L Cracked Block? - 4/18/2008 6:44:45 PM
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Navy85
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Thanks, Kyle. Back to taking the intake manifold apart...
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RE: 4.3L Cracked Block?...New Twist!!! - 4/20/2008 5:00:11 PM
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Navy85
Posts: 15
Joined: 2/24/2008
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Here's a good one for you!
To recap my latest issue...after changing head gaskets and putting the engine back together on my 1996 4.3L 4WD, I was losing about 3 inches of water from the radiator (without the engine running) and it was ending up in the oil pan. Pretty much considered the problem to be intake manifold gasket installation error (gaps in RTV maybe), so I was going to change the gasket and try again.
Instead of "wasting" another intake manifold gasket for what might not be the problem, I RTV'd some gasket material over the water jacket holes with the intake manifold off. After refilling the radiator, I still lost water to the oil pan (had the oil pan drain plug off so I could easily tell when the water flowed).
While I was pouring water into the radiator, I happened to see water flowing out of a small hole (approx 1/4") near the top of the distributor tube. Is just below and to the passenger side of the balance shaft, but inside the hole where the distributor shaft goes.
Now my question...
How is water coming out of this hole?
Anyone know why oil comes out of that hole? Is there a rear bearing for the balance shaft that is being lubricated?
Is there a water jacket passage on the rear of the block that might be cracked?
Would appreciate any thoughts/ideas.
Thanks,
Steve
1996 4.3L 4WD
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RE: 4.3L Cracked Block?...New Twist!!! - 4/21/2008 7:40:10 PM
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Navy85
Posts: 15
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To go along with my previous post...
I've been looking all over the internet for a diagram that shows the rear of the engine block for a 4.3L. Wanting to try to trace oil gallery and/or water jacket on the rear of the block. Any suggestions for where I can find this information?
Thanks.
Steve
1996 4.3L 4WD
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RE: 4.3L Cracked Block?...New Twist!!! - 4/27/2008 1:00:21 PM
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Navy85
Posts: 15
Joined: 2/24/2008
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Just an update...
I spoke with a very helpful mechanic at my local Chevy dealership, and we deduced that the hole where I have water coming from at the rear of the block (inside the distributor shaft hole) is the oil outlet for the rear camshaft bearing. Best he can figure is an internal crack that is allowing one of the water jackets to leak into one of the oil galleries.
Pretty much determined that I just need to pull the engine and have the block checked out. Any last minute ideas that might allow me to not pull the engine?
Thanks,
Steve
1996 4.3L 4WD
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RE: 4.3L Cracked Block?...New Twist!!! - 4/27/2008 1:49:42 PM
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swartlkk
Posts: 15304
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From: Waterloo, NY
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You could remove the intake and water pump, fashion up some block off plates to block the water pump holes and the coolant passages in the heads, then pressurize the system and look/listen for leaks. If the leak were to be caused by a crack in the block, you should be able to locate it fairly quickly.
Have you checked compression after you replaced the head gaskets? Is it possible that there was a problem with the head gasket installation (torque, flatness, etc)?
A leak into the lifter valley (what I assume you are talking about when you say under the distributor) could be caused by an intake manifold gasket failure which I guess you would have fixed in your attempts already. The intake gaskets used on this motor are not meant to have any RTV on any of the sealing surfaces besides the front and back rails of the block. RTV on the overmolded intake gasket will cause it to fail more quickly.
If you do not want to remove the motor, then you have to try other means of eliminating the possibilities.
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Kyle-
My Restoration Projects
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