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Username Post: 1994 chevy 350/5.7L milky oil.        (Topic#365322)
poolguy01 
Newbie
Posts: 10

Age: 71
Loc: Casa Grande,AZ
Reg: 03-30-16
05-25-21 09:52 AM - Post#2820534    

Hello everyone. Its been awhile since i posted here but i am back again to enjoy all the topics in this group. I have a question on my chevy truck as listed above.I don't drive it much but I went for a drive sunday morning.As I was going down the road,it started to miss a little.As I kept driving,the engine started to stall a little and than it shut down.I tried to restart the truck but it would only crank but no start.I had my son pull me to the house.I could hear the fuel pump running. The truck did start the next morning.I checked the water level in the Rad.and it was very low,including the reservoir.It took 2 full gallons of water and still not full.I than said,this is not right.I than checked the oil and the oil was very milky.Darn it,I said bad head gasket,cracked heads,or cracked block.I have a Lisle combustion leak detector and ran a test on the engine.I Ran the engine for about 15 minutes and the fluid in the tube stayed Blue,never changed to yellow or any color.The temperture gauge never showed hot,it barely reached half.So,I need some tips or suggestions on what the problem may be.Is there other things that can cause water in the oil besides what I mentioned here.If I had a blown gasket or anything else,don't you think the truck would be running very hot? Thanks for your help.Sorry for the long post.



 
someotherguy 
Senior Moderator
Posts: 29404
someotherguy
Loc: Texas
Reg: 08-01-03
05-25-21 04:00 PM - Post#2820554    
    In response to poolguy01

I went round and round years ago with the chemical test that wouldn't change colors on a confirmed head gasket failure, turns out it was a bad batch of chemical. Possible it's happened again. In this case though the engine was definitely heating up while going down the road.

I would say another possibility would be engine oil cooler in the radiator (if equipped, and most of these trucks are) has failed and is letting coolant into the oil. Usually you will see oil in the coolant as well.

When the engine is fully warmed up do you see a trail of bubbles in the coolant reservoir bottle? Pretty good indicator of blown head gasket/cracked head.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
thx1138v2 
Contributor
Posts: 239

Reg: 05-01-14
05-26-21 04:46 AM - Post#2820561    
    In response to poolguy01

You said you don't drive it much. Is it possible it sat long enough out in the weather for you to get condensation in the oil pan?



 
someotherguy 
Senior Moderator
Posts: 29404
someotherguy
Loc: Texas
Reg: 08-01-03
05-26-21 09:52 AM - Post#2820570    
    In response to thx1138v2

  • thx1138v2 Said:
You said you don't drive it much. Is it possible it sat long enough out in the weather for you to get condensation in the oil pan?


2+ gallons low on coolant plus milky oil would have me worried.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
poolguy01 
Newbie
Posts: 10

Age: 71
Loc: Casa Grande,AZ
Reg: 03-30-16
05-26-21 12:01 PM - Post#2820579    
    In response to someotherguy

Thanks guys for your replys.I did get another bottle of fluid just in case the one I had was bad or expired.There is no oil in the radiator and no bubbles showing up eighter.I am going to check the compression and also do a Cooling system pressure test on it.Hopefully that will lead me to the problem.I am thinking a bad intake manifold gasket or corroded intake but not sure yet.Will keep you posted.



 
someotherguy 
Senior Moderator
Posts: 29404
someotherguy
Loc: Texas
Reg: 08-01-03
05-26-21 01:34 PM - Post#2820587    
    In response to poolguy01

The intake gaskets can certainly fail; so far I've only seen the TBI engine's intake gaskets fail at the outside edge of the cooling ports, leading to external leaks. It's the Vortec engines (1996-up) that are notorious for leaking internally, but the gasket composition is significantly different. Lots of milky oil cases when those original plastic gaskets failed.

You sound like you have a good plan. Hopefully you got the new bottle of chemical from a different store; maybe even have them check the back stock to see if they have a box that has a lot # (can't remember if the bottle itself does) that you can compare to the original.

No steady trail of bubbles in the coolant reservoir is a good sign! You'll always get some bubbles after a low coolant situation as the system purges air, but that steady trail of them is a fairly sure sign of combustion intrusion into the cooling system.

Hope you get it figured out soon though before that coolant in the oil eats up your bearings.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
CowboyTrukr 
"1`th Year" Silver Supporting Member
Posts: 4622
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
05-27-21 06:17 AM - Post#2820629    
    In response to someotherguy

Speedy identification of the source of the leak and thorough cleansing of the oiling system are vital. I was lazy and didn’t change oil immediately after a blown head gasket replacement. Cost me $2000 to replace the engine. ~$1400 for the engine and the rest was upgrades and regular maintenance parts one normally does when swapping.

The result of my laziness was a spun rod bearing that seized and locked up the #6 if I recall correctly. It broke free from the piston, punched holes in the block on either side just above the oil pan, and cut the camshaft in half. Was not a joyful day in Mudville.

Greg

‘01 Silverado 2500HD 8.1/Allison 1000 Xcab/LB
'00 Explorer XLT 4.0 SOHC V6 Auto
'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500 SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
poolguy01 
Newbie
Posts: 10

Age: 71
Loc: Casa Grande,AZ
Reg: 03-30-16
05-27-21 02:12 PM - Post#2820649    
    In response to CowboyTrukr

Ok, today I was able to do a compression test on each cylinder and most of them read just under 150lbs.Only one was a little low at 145 lbs.For this engine being original,i think the compression is still pretty strong.I was thinking that if i had two following cylinders with low compression,it would tell me that I have a blown head gasket,right? The second test of the combustion leak detector with the new fluid showed no leaks at all,the fluid stayed blue all the time and the temp.stayed at half reading.I am going to take a chance and remove the intake manifold and see if the gaskets are bad or is the intake pretty well corroded and in turn,leaking water in to the oil pan.When I was running it this morning to do the combustion leak test,it sounded nice and smooth.I better drain that water off the oil pan.I don't want to leave it there too long and corroded all the internals of the engine. Thanks to all for your great tips and suggestions.Will keep you posted.



Edited by poolguy01 on 05-27-21 02:14 PM. Reason for edit: No reason given.

 
sjohns4 
Poster
Posts: 69

Reg: 04-21-16
05-30-21 12:26 PM - Post#2820836    
    In response to poolguy01

My old '94 350 developed a leaking intake gasket. Milky oil, loss of coolant. I wasn't loosing it fast as you are however and it was running fine.

A new gasket kit cleared up the problem.

Also, I in my case, the old gaskets didn't show an obvious sign of a leak.




Edited by sjohns4 on 05-30-21 12:30 PM. Reason for edit: No reason given.

 
poolguy01 
Newbie
Posts: 10

Age: 71
Loc: Casa Grande,AZ
Reg: 03-30-16
06-10-21 05:59 AM - Post#2821431    
    In response to sjohns4

I went ahead and removed the intake manifold and the gaskets seem to be ok,cannot see any damage to them at all. The only thing that I saw that I am curious about is this: There are 2 plugs on the under side of the intake.One is there ok but the other I can see right tru.The plug is there but the inside of it is all gone.What is the purpose of this plugs? Im thinking something to do with the EGR system but not sure.Can this bad plug cause the problem I have with the water going directly to the oil pan?



 
someotherguy 
Senior Moderator
Posts: 29404
someotherguy
Loc: Texas
Reg: 08-01-03
06-10-21 07:40 AM - Post#2821436    
    In response to poolguy01

Good catch; if they're the plugs I'm thinking about then they are associated with the cooling passages in the intake. If the passages go to the very front and very rear ports on the intake, that is for the coolant.

Can you post some pics?

If that plug is corroded to the point it failed it would be the first I've heard of; is it possible someone ran that engine for an extended period with straight water instead of coolant mix?

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
poolguy01 
Newbie
Posts: 10

Age: 71
Loc: Casa Grande,AZ
Reg: 03-30-16
06-10-21 10:08 AM - Post#2821443    
    In response to someotherguy

Thanks for your reply and your help. I am not familiar on how to send pictures of the intake manifold so you can all see.The plugs I am talking about are the allen wrench type.The thread looks like a 1/2" type. I think they are called pipe plugs. The Intake is a Edelbrock performance series # 3704. maybe you can see the picture of the intake somewhere online and see the plugs. I don't mean to cause too much of your time.You can do this at your convenience.



 
someotherguy 
Senior Moderator
Posts: 29404
someotherguy
Loc: Texas
Reg: 08-01-03
06-10-21 11:32 AM - Post#2821446    
    In response to poolguy01

Pic found on another site so hopefully it shows up - pretty sure this is the same intake you've got. If you're unsure whether coolant will come through the plug you're looking at, run some water through the coolant ports; they're the four at the outermost corners of the intake.



Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
Fortec Five 
Newbie
Posts: 26

Reg: 03-20-09
06-12-21 05:34 AM - Post#2821516    
    In response to someotherguy

My 1996 Tahoe with the 5.7 Vortex with about 124,500 miles started losing antifreeze, but, it wasn't leaking out on anything I could see. Read on here way back in 2005 that the intake manifold gasket is the culprit. There is a YouTube video on how to replace it...step by step and that is what I did. Sure enough it was the front valley on the block where the antifreeze leaking into the crankcase. I called the dealer on this and they wanted over $800.00 to make the change. I ordered a Fel-Pro gasket kit, and did all it myself for less than $75.00. Also got rid of that Dex-Cool crap that will destroy any engine it is installed in. I found that the antifreeze that got into the oil didn't due any damage, and I still have 65-70 lbs of oil pressure.



 
poolguy01 
Newbie
Posts: 10

Age: 71
Loc: Casa Grande,AZ
Reg: 03-30-16
06-13-21 04:36 PM - Post#2821575    
    In response to someotherguy

Thanks for all the help. I really appreciate it very much. Richard, the picture you show here of the intake is exactly like the one in my truck. See those 2 pipe plugs in the underside of the intake,one of them has a hole right tru it.
I removed the thermostat off the housing and than put water in and the water was coming out the 0ne plug that is corroded instead of just tru the 2 water outlets of the intake.So this is where I was loosing the water and going into the oil pan.I went ahead and replaced the 2 plugs,the intake gaskets,the heater hose fitting in the intake and a new thermostat.I noticed the new new gasket kit did not have any seals for the rear or front of the intake so I just put a 1/4" bead of RTV sealer in that area.I started to put it back together this morning and I am hoping to have it done by tomorrow.Will keep you posted on the progress.Thanks again.



 
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