A little help with a chevy 350

[captmello]

My buddy called me this week and says he's got antifreeze in the oil on his '99 Chevy 3500 w/5.7 ltr. Engine has 175,000 miles.

I'll try to be brief. a little more history is necessary.

Last summer the engine developed a slight "lifter knock" at cold starts. Came and went and he continued to drive it. Once the engine was warmed up a bit the knock would fade and the engine really purrs nice.

So now he's got antifreeze in the oil. I don't know how much but I don't think its a lot. I am not a professional mechanic so my diagnostic equipment is limited to my eyes, ears, compression gauge, and fellow Iboaters.

I thought I'd pull the plugs and give them a read. See if there are signs of antifreeze in the cylinders. If so, I'd plan for an entire top end rebuild provided a wet compression test could confirm no obvious cylinder damage.

if the plugs look good I would do a compression test to look for any bad cylinders. If all the compression numbers came back ok, I guess I'd suspect a bad intake manifold gasket causing the antifreeze in the oil. If the compression numbers come back suspect on one or more cylinders, I'd wet test the cylinders to see what kind of difference that made. If compression jumps up at the wet compression test I would suspect an entire rebuild, if the wet test didn't raise the compression of the low cylinders, I'd assume it to be a bad valve and again probably rebuild the upper half.

At this time I have no reason to believe the engine has any cylinder damage or valve damage.

I know at some point a leak down test could be very helpful but I do not have the tool for that at the moment.

This brings me to my next question regarding the lifter noise. To cure a bad lifter, is it just a matter of swapping the old lifter for a new one? I figured we'd just get a new set of lifters and pushrods. I would do this regardless of whether or not we pull the heads.

Maybe some of you more experienced guys can let me know what I'm missing. Point me in the right direction so to speak.

I'm am going to start working on it tomorrow. I let you know what happens.

 

[Autotech]

Re: A little help with a chevy 350

CaptM Just thought I'd let you know 5.7 GM are notorious for Intake gaskets going bad. Done my share of those. As for lifters they are Roller Lifters new set cost about 350.00. Never replaced a roller lifter on any 5.7 engines. Clean and put um back in I guess they may wear out sometime. The Knock on start up is very common on High mileage GM engines. Usually two places to look Oil pump or Crank Main Brgs. Hope this helps.

 

[windsors03cobra]

Re: A little help with a chevy 350

When you see the gasket design you will wonder how its held on this long, especially when the engine comes apart and the gasket is all rotted away and broken into pieces YUMMY.

GM: We can screw up good engines like the 350 and Buick 3800 by doing mickey mouse intake re-designs and introducing **** poor coolant.
I wonder why GM is bankrupt. :redface:
Atleast GM's new V8 have a dry intake.

 

[dr_bowtie]

Re: A little help with a chevy 350

agreed..the intake gaskets are toast...use the old style felpro t fix it...

I had a lady bring in a Yukon last year and she called and said the antifreeze would just disappear and she would have to refill it every 10 miles...

by the time she finally brought it in the engine had no oil and the crankase was full of antifreeze....

Orange has alot of lubricity and thats the only thing that saved the enige...she drove it that way for weeks...I pulled it all apart and there was a scratch on any bearing or journal and the inside was very clean...that thing help a constant 30psi pumping anitfreeze...

 

[captmello]

Re: A little help with a chevy 350

agreed..the intake gaskets are toast...use the old style felpro t fix it...

I had a lady bring in a Yukon last year and she called and said the antifreeze would just disappear and she would have to refill it every 10 miles...

by the time she finally brought it in the engine had no oil and the crankase was full of antifreeze....

Orange has alot of lubricity and thats the only thing that saved the enige...she drove it that way for weeks...I pulled it all apart and there was a scratch on any bearing or journal and the inside was very clean...that thing help a constant 30psi pumping anitfreeze...

Orange is the color my buddy described over the phone.

I'm going over there today to pull the plugs and do the compression test.

I have a couple more questions.

1. Should I run the engine before doing the compression test in order to get a more accurate reading?

2. To determine which lifter/s is suspect for being sticky, can I pull the spark plug wires off one at a time to narrow it down to which cylinder? How would you guys handle the lifter repair? Or should I pull all the lifters and clean?

Thanks for all the help!!!

I'm working on this truck this afternoon. Hope it warms above 10 deg F. today. Another reason to warm the engine before working on it outside.

 

[truckermatt]

Re: A little help with a chevy 350

i would get a coolant pressure tester and test the system when cold... that way you will see the leak if its external...

I could be the intake gasket, or many other things.... i have the engine block heater plug on mine leak and my coolant was low every week...

But fix is soon or the antifreeze will eat your bearings away fast.... watch the oil pressure too. change the oil after it s fixed...

are you sure you have coolant in the oil.. did you run an oil sample in a lab... or are you just assuming since the coolant is getting lower.

 

[Gary H NC]

Re: A little help with a chevy 350

My bet is the intake gaskets too....
They usually leak in the rear where the head meets the block and intake.
Feel back there and i bet you will find antifreeze.

Felpro has an updated set called Perma-seal for the GM 350.

I replaced mine about a year ago and no problem since.

Be sure to tighten the intake bolts to specs...I think it was only 12 or 14 ft pounds.DO NOT over tighten them.

 

[captmello]

Re: A little help with a chevy 350

i would get a coolant pressure tester and test the system when cold... that way you will see the leak if its external...

I could be the intake gasket, or many other things.... i have the engine block heater plug on mine leak and my coolant was low every week...

But fix is soon or the antifreeze will eat your bearings away fast.... watch the oil pressure too. change the oil after it s fixed...

are you sure you have coolant in the oil.. did you run an oil sample in a lab... or are you just assuming since the coolant is getting lower.

I thought about a pressure test but I don't have the tool and it's not leaking externally.

According to my buddy, the oil cloudy and orange colored.

You mention it could be many other things, like what? headgasket, cracked block? I'm hoping that if It is a head gasket, it will show up as low compression in a compression test. I really doubt the block is cracked.

I just don't want to pull the heads if we son't have to.

 

[captmello]

Re: A little help with a chevy 350

My bet is the intake gaskets too....
They usually leak in the rear where the head meets the block and intake.
Feel back there and i bet you will find antifreeze.

Felpro has an updated set called Perma-seal for the GM 350.

I replaced mine about a year ago and no problem since.

Be sure to tighten the intake bolts to specs...I think it was only 12 or 14 ft pounds.DO NOT over tighten them.

Thanks,

I googled and found these specs.

http://boxwrench.net/specs/chevy_sb.htm

Also says non hardening sealer. I have some Permatex #3 aviation sealer, should work. And 30 ft lbs. torque for cast intake.


I also recall using rtv in the corners buy the rubber end gaskets, right?

What about the lifter knock? Not sure if I should pull all the lifters or try to identify which lifter or lifters are knocking and just work on those.

I just don't want to do extra work or have to do it twice.

 

[itsaboattime]

Re: A little help with a chevy 350

Years ago, you could rebuild lifters. I don't know if thats the case here.

Having said that, I'd definatley check all of them for wear, and clean them all real well. You should be able to identify the "noisy" one.

 

[Jeep Man]

Re: A little help with a chevy 350

Cause is most likely gaskets. If you are changing the intake gasket, do the head gaskets as well, and visa versa. Have the heads planed, they have a tendency to warp slightly upon removal. Also have the heads checked for cracks. 350 parts are relatively inexpensive. Price out a set of aftermarket heads with lifters. You can fix the knock at the same time. At 175K, it's due for a minor overhaul.

 

[Gary H NC]

Re: A little help with a chevy 350

I think those torque values were for the non-vortec cast iron intake.
30 ft pounds sounds like way too much.

The gasket set is Felpro# MS 98000T
Use black or orange Permatex gasket sealant on the front and rear lip.
The aviation sealant is too thin...DO NOT USE.
Run a thick bead and extend it up onto the intake gasket just a bit.

Just found the torque specs..i wrote them on my gasket box,
First round tighten them to 44 inch pounds,then go back and tighten to 89 inch pounds.
That info came from my local Chevy dealer.

That gasket set includes the gaskets to remove the plastic part or plenum of the upper intake.
You do not need to do that.Pull the intake and fuel injection all as one piece.

Also all of the wire connections are different so its east to get everything plugged back in to the right place.

My neighbor and i done the whole job in 8 hours start to finish.

The gasket set comes with only one valve cover gasket because that is all that is needed to remove the intake.(remove drivers side valve cover)
I ended up just buying a set and replacing both valve cover gaskets with the thick blue rubber Felpro set.

 

[Gary H NC]

Re: A little help with a chevy 350

Just gave a call to the Chevy dealer on the torque specs.
If using a foot pound torque wrench tighten the first round to 6 ft pounds,then go back and tighten to 9 ft pounds,final pass do not exceed 12 foot pounds.

 

[captmello]

Re: A little help with a chevy 350

Thanks Gary, that is great info!!

12 lbs., just like you said.

Use black or orange Permatex gasket sealant on the front and rear lip. Run a thick bead and extend it up onto the intake gasket just a bit.

I've got some prematex black high temp rtv gasket "Maker." Thats what I used on my 350. Are you also saying to use that instead of the rubber gasket on the front and back or in addition to them?

Whats your take on the lifters. Remove all, clean and reinstall. Or, find which lifters are knoking and service only those. I'm leaning toward removing all the rockers, rods and lifters, cleaning them, and reinstalling. I plan to adjust the valves with the engine running.

 

[jeeperman]

Re: A little help with a chevy 350

I always thought there was no valve adjustments to be made with hydraulic lifters?

My 1999 5.7L Tahoe is doing the exact same. Has 115k miles on it.
Lifter knock upon start up 50% of the time. Does not seem to matter how hot or cold it is nor how long it has sat since last start up.
Goes away in 20 seconds to 3 minutes.
My coolant is leaking out the backside of the intake/block/heads joint.
Although the oil is clear, there is antifreeze condensed under the inside of oil fill cap.
So at least a tiny amount is leaking internally.

 

[Gary H NC]

Re: A little help with a chevy 350

The gasket set for the Vortec does not include a rubber gasket for the front or rear of the intake.
There is no oil pressure there at all so the bead of Permatex is all you need.
The black gasket maker is fine.

On the lifters i am wondering if the oil diluted with anti-freeze could be causing the sound.It would sure lower the viscosity of the oil.
Heck if was going to pull all the lifters i would put new ones in.

 

[windsors03cobra]

Re: A little help with a chevy 350

If he's been tooling around with a crankcase milkshake in there for anything longer than a ride or 2 home the lifter tick is going to be the least of his worries.
And if that crankcase milkshakes truely is nasty and you's guys fix that truck it would be a good idea to kinda flush out the crankcase with a oil change shortly after its fixed in addition to the pil changes you do while fixing it.

 

[captmello]

Re: A little help with a chevy 350

Here's an update.

Temps climbed up to 7*f yesterday afternoon so we headed out to look it over. Before running it, checked the oil. It showed a little overfull. Perhaps a half quart over and the oil was orange and murky.

I found out a little more info on the truck. It turns out the upper half of the motor had been done about 70,000 miles ago, at about 105,000 mles, but he had no further details on why and what exactly had been done. It cost him $2,200 about six years ago.

Also, there is an antifreeze leak at the far back or the engine. I'm thinking its also the intake, but I'm not familiar enough with the cooling system to know if that's a possibility and we couldn't see where it was coming from exactly. It's running down the passenger side of the bell housing.

So we ran the truck for 10 minutes to warm up the engine for the compression test and to make it warmer to work on.

Even after ten minutes of warm up, you could still put your hand on the exhaust manifold, it was perfect for working on. We pulled the plugs. The plugs were a bit old but all seemed good light brown color, The plugs on the drivers side had some Ash deposits, presumably from burning oil, which I figure would be valve guide leakage. He says he burns a quart of oil every thousand miles. I'm not sure what to make of that.

What do you guys think?

We continued on with the compression test. All cylinders were right at 175 psi. I was really impressed by that. However I don't know what the specs should be for that motor.

We put a new set of plugs back in and went to warm up.

So thats were we stand. I told my buddy he has to find out where the antifreeze is leaking from at the back of the motor before we start tearing into it.

What we can't decide is, do we just do the intake gaskets, pull and clean or replace the lifters and reassemble without pulling the heads, or do we pull the heads and spend the extra work and money to pull and machine the heads "While we're in there". What are the chances a bad head gasket could be leaking the antifreeze into the oil and not the intake gasket?

What is the most practical thing to do? Budget is always a factor, but we only want to do this once.

Thanks again to all for your help.

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[Gary H NC]

Re: A little help with a chevy 350

Antifreeze dripping off the bell housing and coming from the rear of the motor is 99.9% intake gasket leaking.
The compression sounds good.Pulling the heads and having new valve guides and seals would probably stop the oil usage unless he has a leak somewhere.

If it were mine i would do the intake gaskets and not pull the heads...just way less work.

 

[windsors03cobra]

Re: A little help with a chevy 350

Yeap the antifreeze enters and exits the coolant on each of the 4 intake manifold corners and every 100 grand is about right on those I was kinda doubting they were original at 175K.
With 175k on it I would fix the intake and run'er some more I would not remove the heads either. I wouldn't mess with the lifters either.
Maybe a new set of lifters if he is so inclined and the money is right.
Lifters should not be that expensive.

Working outside on that type of stuff in this weather is nuts, course I was sledding in it all day yesterday but atleast that is fun but frustrating when your buddies sled dies and your the tow sled. :redface: