2002 Avalanche engine locks on start

[Jay Hocke]

The other day my 02 Avi 5.3L with 250,000 miles locked up while starting it.  To make a long story short, I believe it was hydro locked as I found a fair amount (about 1 oz.) of coolant in the #6 cylinder.  I had been losing a slight amount of coolant for some time.  I had a leak around the water pump area and attributed the leak to the gasket failing.  Oil filler cap is dry.  Changed oil looks normal, no change in look and texture from one change to the next.  Read about the failed Castech heads.  Could they lead coolant into the one cylinder? If not, how about the likelihood of a head gasket fail? The miles are mostly long distance miles on cruise control. Engine has always run smooth up to this moment.  No lifter noise, no knocking, maybe a slight loss of performance as the plugs have never been changed.  250,000 miles must be some sort of record. I have put a camera into each cylinder and the only one with liquid is #6.  Appreciate any help.  Not going to dealer as this is my baby.

[Jsdirt]

Only 2 ways coolant can get in there, and you've mentioned both - cracked heads, or blown gasket. At that mileage, either is very possible, and probable.

 

Smart man, keeping that thing away from the dealer. 

[Jay Hocke]

Thanks, JS.  As soon as I get it back together, I am going to compression check #6.  Not sure if it won't tell me anything I don't already know.  I am thinking of I get the head removed I might have it magnfluxed to tell me if there are cracks.  If no cracks, I can be relatively certain it might be just a head gasket replacement.  If that so, I will remove both heads and get them rebuilt along with some new lifters.  Anything else you can think of that might be advantageous short of getting at the lower end too? 

[Jsdirt]

No problem, Jay.

 

You might be able to hook up a smoke machine to #6 with some adaptors, and possibly find it that way. Another option is a regular leak down tester - might be able to find the air escaping a cracked head using some Windex,  or soapy water with the valve covers off. Try it first with just the oil coating before using any soapy spray - it might be obvious. Only use spray if you can't seem to find it - less worry about having to clean all of that out of the engine. Since the leak filled that cylinder up, I'd imagine it's a good sized one - should be fairly easy to find. Look for bubbles in the radiator or tank too when it's under pressure - that'll confirm the head gasket.

 

If the truck is rust free, and you plan on running it many more years, I'd highly suggest a timing chain and oil pump at the very least for the lower end. Preferably a new long block (block & heads all new and assembled). If you're looking at maybe another 3-5 years before the body blows out, then you can get away with doing a thorough inspection of the head for cracks, and valve leakage, replacing anything worn out. Can go with junkyard heads if you only plan on a year, or not much longer. Don't forget a new set of ARP head bolts if you're looking at more than 5 years (stock bolts if not), and all the related gaskets & seals for the job.

 

It's always tough to figure on these ones. You don't want to spend alot if the body or frame is on it's way out soon. But by the same token, if it's in great shape and you plan on keeping it indefinitely, where do you stop with repairs? Can get to be a wormhole - I've been there, except I miscalculated the life of the body on mine, and spent WAY too much money, and WAY too many hours of my labor.

 

How the wormhole begins:

 

Since you removed the heads, why not replace the cam & lifters ..... since you removed the pan for the oil pump, might as well slap some bearings in the lower end .... since I'm unbolting the rods, might as well slap some rings in there and give her a light hone ... and on and on it goes.  

[Jay Hocke]

I started my wormhole 3 years ago by cutting out the rust and butt welding new metal in its place.  Turned out really well as no one can spot the repairs above the cladding.  I bought it new and can't seem to want to get rid of it.  It is just fun to keep changing appearances and working on the engine and suspension.  My 92 yr old Dad thinks I am crazy.   He is a Ford guy and what would you expect him to say? LOL!  He loves to rub it in that I am a Chevy enthusiast.  I like Ford trucks too, but, my Avi rides better and they don't make them anymore.  Kind of like that el Camino.  I had one of those two.  It was a rust bucket from Michigan. But, I wish that I had it today.

[Jsdirt]

I hear that - I'll be doing the same thing with my '07. The way I figure it, for the $30 LARGE it cost me to buy it, I need a MINIMUM of 30 years out of it.   Going to be a tough run for me, the way they build stuff today ...  Like buying a $6,000 vehicle every 5 years, which I'd be doing anyway if I wanted a modern vehicle.

 

I used to be a die-hard GM guy, but I've owned a Ford right along side my Chevys for the past 15 years. They all have their quirks. I like having the distributor up front on the Grand Marquis - makes things easy.

 

I'll tell you though ... after 1994, there is no difference between any of them. They're all built with a beer can body, cheap, thin, substandard copper wiring, bearings with one-ten-thousandth of a CC of grease in them ... and  to top it all off, these days they're now cheaping out on critical engine components, like lifters, cams, timing chain guides, plus designing systems that fail just outside of warranty. Sad state of affairs in the automotive world today. But, they're shiny and nice looking, handle great with great power .... UNTIL THEY BREAK ... then the fun begins! People will keep buying them, and paying more than our parents paid for their first house, because they can't see past the shiny exterior. I've got friends that just bough spankin' new Chevys, and have been in and out of the dealer for warranty work ever since. " I should've listened to you! " Starting to hear that alot these days ...

 

Next new car I buy will be built prior to 1973. I'll be glad to take out a loan on a vehicle I will build myself, using tried and true driveline and electrical components. It's pretty clear that nobody can do that for me these days, aside from maybe those custom guys on TV out in CA. I don't have pockets that deep, unfortunately. 

[Swimmer8366]

Sounds like a perfect time to do adoption 6.0 swap......?

Sent from my Z981 using Tapatalk

[Jsdirt]

Once I make it through the next 5 years with mine, I'll be doing a 502 swap. 

[fjay0916]

3 hours ago, Jsdirt said:

I hear that - I'll be doing the same thing with my '07. The way I figure it, for the $30 LARGE it cost me to buy it, I need a MINIMUM of 30 years out of it.   Going to be a tough run for me, the way they build stuff today ...  Like buying a $6,000 vehicle every 5 years, which I'd be doing anyway if I wanted a modern vehicle.

 

I used to be a die-hard GM guy, but I've owned a Ford right along side my Chevys for the past 15 years. They all have their quirks. I like having the distributor up front on the Grand Marquis - makes things easy.

 

I'll tell you though ... after 1994, there is no difference between any of them. They're all built with a beer can body, cheap, thin, substandard copper wiring, bearings with one-ten-thousandth of a CC of grease in them ... and  to top it all off, these days they're now cheaping out on critical engine components, like lifters, cams, timing chain guides, plus designing systems that fail just outside of warranty. Sad state of affairs in the automotive world today. But, they're shiny and nice looking, handle great with great power .... UNTIL THEY BREAK ... then the fun begins! People will keep buying them, and paying more than our parents paid for their first house, because they can't see past the shiny exterior. I've got friends that just bough spankin' new Chevys, and have been in and out of the dealer for warranty work ever since. " I should've listened to you! " Starting to hear that alot these days ...

 

Next new car I buy will be built prior to 1973. I'll be glad to take out a loan on a vehicle I will build myself, using tried and true driveline and electrical components. It's pretty clear that nobody can do that for me these days, aside from maybe those custom guys on TV out in CA. I don't have pockets that deep, unfortunately. 

Yeah. I am with you.  I cannot justify a truck payment that will put me into economic slavery for 10 years. For now it is Mad Max apocalypse time.  I will keep fixing up the old one like i live in a third world country.  

[fjay0916]

I am back and really pissed. I found out I had Castech heads and decided to purchase a remanned one from Allied Motor Parts. They told me they fix all of the Castech problems and guaranteed it. Fine. I get the head and did a cursory inspection. Everything looked all right. So I remove the old head and took apart most of the top part of the engine. got a gasket set and new head bolts. Put the new gaskets and new head on. Went through the process of head bolt installation. Long story short is everything is assembled and I start putting in the coolant. Gets up to the head and I hear a gushing sound of coolant leaving the head and hitting the floor. I am panicked at this point. Failed to say that while putting in the intake the bolt hole closest to back of head #8 in the sequence, tightened on first torque pass to 3.5 ft. lb., but, on second pass at 7.6 ft. lb. it would not and when backed out there was a helicoil on the bolt. Pissed. So I drilled for a ez-lok threaded insert and installed. Perfect. Helicoils are junk. Threaded inserts are the way to go. Anyway, I never looked at the freeze plugs before putting in the head and when I looked for the leak, what did I find? A freeze plug with a split in it. 4 days to get this thing installed and all for not. Allied Motor Parts in Atlanta. AVOID THESE CLOWNS AT ALL COST. If that freeze plug was split and they did not fix it and they sent this head out with a damaged bolt hole and claimed this was a re-manufactured cylinder head, would you trust it? In my business, one does not use the re-manufactured word lightly. Allied Motor Parts has not answered one of my three emails or voice mail.

[fjay0916]

Yee Haw!!! I am happy to report that after taking my old castech head to a local parts store that rebuilds heads and had it pressure tested, they found no leakage and no warping.  The guy who did the test suggested that the multi layer gasket probably deteriorated and was the cause of the leak.  So I had him clean it up and installed it with a new head gasket and have been driving it for 3 weeks.  It runs great and I am ecstatic!  Paypal came through for me an secured a refund on the failed head.  All is good now.  My baby is running and I could not be happier.  The head gasket was my first guess when troubleshooting the problem, but, so many people have had the typical castech head problems, I went with that.  Should have went with my gut.  The difference in my case is that my truck had 244,000 mile on it and most with the typical castech problem had low mileage vehicles 60,000 to 150,000 miles.  Also, I had no coolant in my oil like they would have suffered.  My leak was in the cylinder.  Also, changed my original sparkplugs and got rid of my misfires. Trust the Force, Luke!    She loves to romp in the snow.