99 4.8 Lr4 Coolant In Oil

99_4.8_LR4 · August 18, 2009

I have a 99 GMC Sierra (new body style) with the 4.8 LR4 Gen 3 , 170k miles . The truck started using a small amount of coolant over long periods . I would always keep it topped off. The truck has always run great , with no steam from the exaust etc. Recently the coolant loss had gotten worse , and upon pulling the dip-stick the other day I found that my oil was completely brown . Obviously the Dex-Cool has worked its way into the oil.

It still runs like new and doesn't steam or smoke out of the exaust or skip .

I have seen the TSB about Castech heads on several sites , but I see the TSB is for model years 2001-2006 . Did GM use Castech heads in 99 ? I have pulled the valve covers and they are loaded with orange goo , however I did not want to tear it down further to look for the Castech logo .There were no washed out spots in the oil drains as described in the TSB .

Going to drain/flush/change the oil today and dump some Bars Leak in the coolant and see what happens .

Anyone had the same problem with a (pre TSB) 99 4.8 LR4 ?

superjim · August 18, 2009

Check for leaks around the intake gasket.

99_4.8_LR4 · August 18, 2009

Check for leaks around the intake gasket.

The LR4 does not have coolant in the intake .

I see this was a common problem with the older v6 and v8 though .

99_4.8_LR4 · August 19, 2009

A little update .

Went out to the truck yesterday after it was sitting for a couple days . Pulled the dip stick and the "oil" level (or in my case oil + dex cool) was about 2 inches higher than before . Coolant tank was almost empty just from sitting .

I drained the "oil" and left the oil drain plug out over night .

I went out to the truck about 10 minutes ago and placed the oil drain plug back in for 2 mins. Pulled the plug again and got pure Dex-Cool mix, about 1/3 of a QT. This thing just pisses Dex-Cool right into the oil pan , lol .

I am going to rule out this motor having Castech Heads on it , as it is a 99 , not 01-06. This engine had never used even a drop of coolant in over 140k miles, and like I said I have had the valve covers off and it shows no signs of washing in the oil drains . I see that most people with Castech heads have had problems with slow coolant loss much earlier than this . Not to mention that these Castech crack problems dont just dump this much coolant in the oil while just sitting for 2 minutes with no pressure on the cooling system .

The head number is 862 , btw .

So I guess it is either a blown head gasket , or the block . I seriously doubt that it is the block , this engine has never been overheated or frozen . I guess I will just pull the heads and have a look .

99_4.8_LR4 · August 28, 2009

Update

Pulled the heads today with myself and my father . Saved about $800 -1000 of labor too .

My heads are not Castech like you 02-06 guys out there .

It took 5 hours flat to remove both heads which includes clean up with 2 guys wrenching and I must say these engines are an absolute cake walk to work on .I bet the dealer would have put one guy on this so he could charge me for 10 hours .

All you need is an 8 mm socket , a 10 mm socket and a 15 mm socket , well several models in different drives from 1/4 to 3/8 to 1/2 " as well as some extensions of various lengths , a 1/2 " breaker bar and various ratchets and some etc tools like a GM fuel line removal tool . And a little know how.

Basically there is alot of fiddling with the wires etc on the intake then it is just pure butter . All the exhaust manifold bolts came out nicely except the one that must have snapped it self off years ago . I heard they had some trouble with weak bolts in these .The manifolds slide just far enough out of the way once both are off to get a socket on the outer head bolts near the plugs.

The only small gripe is that the outer rear head bolts are too long to be removed without lifting the heads up . They are simply too long and hit the firewall.

Anyway the head gaskets completely failed in between the oil and coolant passages , as I had hoped . The passenger side had no leakage into the cylinders while the drivers side showed very , very minimal weepage (not leakage) into three cylinders . The cylinders look brand new with 170k miles.

The corrosion from the Dex Cool was obvious and it looked like it just ate the head gaskets for breakfast .

Anyway the heads are going in for cleaning and surfacing and I should have the top end gasket set soon . Cant wait to spend about 10 hours putting her back together .

If you buy or own one of these trucks with high miles , make sure it has had or gets head gaskets !

jrrod2004 · August 28, 2009

Update

Pulled the heads today with myself and my father . Saved about $800 -1000 of labor too .

My heads are not Castech like you 02-06 guys out there .

It took 5 hours flat to remove both heads which includes clean up with 2 guys wrenching and I must say these engines are an absolute cake walk to work on .I bet the dealer would have put one guy on this so he could charge me for 10 hours .

All you need is an 8 mm socket , a 10 mm socket and a 15 mm socket , well several models in different drives from 1/4 to 3/8 to 1/2 " as well as some extensions of various lengths , a 1/2 " breaker bar and various ratchets and some etc tools like a GM fuel line removal tool . And a little know how.

Basically there is alot of fiddling with the wires etc on the intake then it is just pure butter . All the exhaust manifold bolts came out nicely except the one that must have snapped it self off years ago . I heard they had some trouble with weak bolts in these .The manifolds slide just far enough out of the way once both are off to get a socket on the outer head bolts near the plugs.

The only small gripe is that the outer rear head bolts are too long to be removed without lifting the heads up . They are simply too long and hit the firewall.

Anyway the head gaskets completely failed in between the oil and coolant passages , as I had hoped . The passenger side had no leakage into the cylinders while the drivers side showed very , very minimal weepage (not leakage) into three cylinders . The cylinders look brand new with 170k miles.

The corrosion from the Dex Cool was obvious and it looked like it just ate the head gaskets for breakfast .

Anyway the heads are going in for cleaning and surfacing and I should have the top end gasket set soon . Cant wait to spend about 10 hours putting her back together .

If you buy or own one of these trucks with high miles , make sure it has had or gets head gaskets !

or replace the dexcool alot quicker....say every year and a half

99_4.8_LR4 · August 28, 2009

or replace the dexcool alot quicker....say every year and a half

Who said the coolant was never replaced ?

Dex Cool is rated for 5 years or 150,000 miles .

Dex Cool just eats gaskets period .

It is well documented and includes lawsuits .

rodram · August 28, 2009

I don't know how anyone can rate Dexcool or any coolant product for 5 yrs/150,000 miles. If you want to protect your head gasket and/or intake manifold gasket, then you have to check the pH of your coolant... no matter what type you have.... and when it gets below a critical number then it is time to flush and change the coolant.... some engines are more prone to making the coolant acidic faster ... some GM gaskets are prone to failing rapidly ... when replacing your head gasket you should NOT use the GM replacement or you will just be doing it again sometime soon.... find the new FELPRO gasket kit, check your pH regularly, and you will likely not have to replace another head gasket in this truck.

jrrod2004 · August 28, 2009

or replace the dexcool alot quicker....say every year and a half

Who said the coolant was never replaced ?

Dex Cool is rated for 5 years or 150,000 miles .

Dex Cool just eats gaskets period .

It is well documented and includes lawsuits .

I never said that it was replaced but I did work for GM in the past and they knew that once the PH levels went down, Dexcool became acid to the gaskets. Most dealers agreed that 1 to 1.5 years was a decent amount of time they would recommending changing...I dont mean to be an ass but some of our trucks are rated for towing of 10,500 LBS but it is not recommended to consistently tow at that load. Same goes for Dex Cool.

Draenor · August 28, 2009

or replace the dexcool alot quicker....say every year and a half

Who said the coolant was never replaced ?

Dex Cool is rated for 5 years or 150,000 miles .

Dex Cool just eats gaskets period .

It is well documented and includes lawsuits .

txab · August 28, 2009

This is turning into another coolant thread.

99_4.8_LR4 · August 29, 2009

I don't know how anyone can rate Dexcool or any coolant product for 5 yrs/150,000 miles. If you want to protect your head gasket and/or intake manifold gasket, then you have to check the pH of your coolant... no matter what type you have.... and when it gets below a critical number then it is time to flush and change the coolant.... some engines are more prone to making the coolant acidic faster ... some GM gaskets are prone to failing rapidly ... when replacing your head gasket you should NOT use the GM replacement or you will just be doing it again sometime soon.... find the new FELPRO gasket kit, check your pH regularly, and you will likely not have to replace another head gasket in this truck.

Yeah I understand about regular flushing , PH etc . Coulda Woulda Shoulda .

Looks like GM could have put some way nicer head gaskets in these. The look really cheap with no beefy seals between the coolant passages and the push rod galley , oil galleys , or even the head bolts . Mine was draining coolant out of the outer head bolts with just 1 taken out . Yah I guess I could have drained the coolant off a bit lower , but this goes to show how well that head gasket was holding up . BTW I would rate these OE head gaskets for a maximum of 100k miles .

I will definitely get some Fel Pro gaskets for it , at least for the heads .

I never said that it was replaced but I did work for GM in the past and they knew that once the PH levels went down, Dexcool became acid to the gaskets. Most dealers agreed that 1 to 1.5 years was a decent amount of time they would recommending changing...I dont mean to be an ass but some of our trucks are rated for towing of 10,500 LBS but it is not recommended to consistently tow at that load. Same goes for Dex Cool.

Yeah so GM knew the coolant wouldn't hold up . What the dealers do is just let everyone run the coolant until it is acid . $$$$$$$

This is turning into another coolant thread.

Acid-Cool

ShoddyHog · August 29, 2009

It absolutely HAS to be DexCool. I've never, ever had a head gasket blow with the green shit. Never heard of it either. Blown head gaskets only happen with DexCool.

Don't forget to use distilled water with your DexCool.

Gerry

superjim · August 30, 2009

It absolutely HAS to be DexCool. I've never, ever had a head gasket blow with the green shit. Never heard of it either. Blown head gaskets only happen with DexCool.

Don't forget to use distilled water with your DexCool.

Gerry

I think I vaguely, sorta, kinda, remember a gasket or two blowing...way back then, when I was using the green stuff.

PLUS ONE on using distilled water with the Dexcool.

Using plain old tap water can leave silicate deposits on the inside water passages, and decrease the heat absorbing ability of the coolant.

This applies especially to aluminum engines.

ShoddyHog · August 30, 2009

It absolutely HAS to be DexCool. I've never, ever had a head gasket blow with the green shit. Never heard of it either. Blown head gaskets only happen with DexCool.

Don't forget to use distilled water with your DexCool.

Gerry

I think I vaguely, sorta, kinda, remember a gasket or two blowing...way back then, when I was using the green stuff.

I also remember heads weighing a TON compared to these aluminum ones.