Hello everyone here at this forum.I'm trying to figure out what might be the problem with my chevy truck.Engine is a 5.7L Tbi type. Since I retired 2 years ago,I only drive this truck once a week or so.I bought it brand new in 94.Here is the problem.I was driving the truck monday here in town to do some shopping.As I was going down the road,the engine started to hesitate some.I did not fill comfortable with it so I drove home.The truck was not overheating at all.I decided to check the oil and it was all milky looking. After the engine cooled down,I checked the coolant in the radiator and it looked like it had oil in it.I drained a little coolant and I felt the coolant and yes,it was oil,slippery. So,my first thought was a bad head gasket,a cracked head,or a cracked block.So, I did a combustion leak detector test and that turned out ok,the liquid in the tube stayed blue all the time I ran the truck (about 15minutes). It did not change to a yellow color showing any of the above being bad.Than I did a compression test and all the clylinders had 150 lbs of pressure except one which had 146 lbs.I consider this a pretty good pressure (unless you guys think otherwise).So, I than said,its got to be the engine oil cooler inside the radiator bad so I removed the radiator and got a new one.This rad.had a lifetime warranty on it.Glad it did,that rad.cost $200.00.After replacing the new rad.,I filled it up with Distilled water (for testing purposes only).Started the truck up and ran it for about 15 minutes. Guess what,the engine oil dipstick is milky again. However,the water in the rad.is clean,no oil in the water like before. I'm lost with idea's now so need some help with this problem.Could I still have a bad head gasket or head eventhough the test was good. I would apreciate any and all the help that I can get from you guys or gals if there are some here.Thank you kindly.
PS- I don't want to start changing parts that are not the problem.

 

I don't see in your post if you changed oil and filter.

 

It's possible intake manifold leak. You proved it's not from the transmission.

 

Yes,right after I replaced the radiator and filled it with water,I than dumped the oil out ( mostly water out of the pan) and put in new oil and filter. Could it be that there was still water in the engine and thats why its still showing a milky oil. I don't want to tear into the intake manifold unless its going to take care of the problem. The intake on this truck was replaced about 6 years ago because it had an external leak. I guess it could still be bad or the gaskets. I checked again and the water in the radiator is nice and clean,no oil in it. I wonder if I should run the truck some more to let all the excess water get circulated within the engine and than dump the oil again and put in a new oil and filter.I hate just wasting money but if thats what it takes to get this truck back to normal,I will do it. Thanks to you guys and gals for your input on this matter.

 

Might be residual, run it, and check later.

 

Well,still struggling with this problem of coolant in the oil . The coolant in the radiator is clean,no more oil in it after the new radiator but still showing a milky oil dipstick. I was going to change the oil and filter again but before I put in the new oil, I had my wife put in some distilled water in the radiator just for testing purposes and while she was filling up the radiator,I was under the truck looking at the oil drain plug.Guess what,the water was coming out the oil pan drain plug as fast as she was putting in the water. Looks like i have a big leak somewhere in the engine, not an external leak. Would the intake gaskets or a bad intake cause this problem? Trying to figure out the culprit. Thanks to all for your help and suggestions .

 

Sure could, but that is one bad leak if it's going straight into the pan. You need to get all the antifreeze out as it will damage your bearing much faster than water/oil will. Likely a very bad head gasket leak and/or intake manifold leak. If you pull the head's you'll need to surface them for warpage before you re-install them.

 

I went ahead and removed the intake manifold today.The gaskets seem to be ok,no tears anywhere. I do have a question on the intake. There are two plugs on the underside of the intake.One is fully pluged but the other plug,its just a hole.Maybe the inside of it rotted out or something cause I can see all the way tru it. If this one is suppose to be plugged too and its not,can this be the cause of the coolant going directly to the oil pan? Not familiar with this problem.
Thanks for your help.

 

It looks like the problem is one of the pipe plugs that Edelbrock put on the underside of the intake that got corroded and left just a hole open,letting all the water go right tru it and into the oil pan. What I did was remove the thermostat and than put water in and as I did,I could see the water come right out of that plug and into the liffter valley and onto the oil pan. So, I replaced the 2 plugs,new intake gaskets,new heater hose fitting in the intake,and a new thermostat. I started to put it back together today and hopefully will get it done tomorrow. Will keep you posted on how its coming along.Thanks for your help.

 

I put everything back together yesterday. Have new pipe plugs on the lower intake,new intake gaskets,new thermostat,new upper radiator hose. I also flushed the coolant 3 times since there was oil in the coolant. I also replaced the radiator since it was under warranty. I than started the truck up and ran it for about 15 minutes. Ran good,no leaks anywhere. There is a problem though that I cannot understand and I am hoping that one of you experts can help me out. After running the truck for 15 or so minutes,the temperature gauge will not go even half way on the gauge.On my truck,there are 3 settings,100,210,and 260 at the end. The needle will only go as high as about 125 or 130,no higher than that. Before all this happened,it would always be around 210 constantly. I checked the gauge and its ok.I thought it might be a bad temperature sender switch (or sensor) and after replacing it,it made no difference at all. This is the one between spark plug # 1 and spark plug #3 .The other sender,the one that communicates with the ECM, the one by the thermostat,I replaced last year. I am lost as to what might be the problem. Can you guys or gals give me some advice or tips on what to check next? Could it be the fan clutch or a bad water pump? Remember,it all started when the oil was getting alot of water. Thanks for all your help.I am hoping that with your expert help,I will be able to fix this truck to normal condition.