Blown Heads

[99Tahoe-20/20]

Okay so I took the Tahoe in today to have the missing cooland looked into. Its a 99 with 5.7 ltr, 78k on it. Never over heated or froze. The IM gaskets have been replaced I think twice now. First time they were leaking second time they were weaping and it was under warranty so they swapped them out. Now that the extended warranty is out, it looks like the heads are gone.

Shop is telling me there is substantial water in the oil. I know this from the white paste on the filler cap. They also are indicating there is cumbustion gasses in the water. This all points to a head or headgaket. In their opinion, the heads are probably cracked 9 times out of ten on these things due to the poor design. They want 2,500 to RR the heads and replace them both if needed. Plus tax your looking at 3,750 or so. Uggg! 3,750 into a 8k car. Ouch!

So my question is, how hard is it to do this job myself? I have mostly worked on small European motors of the 1960 veriety with twin cams, etc. I have rebuilt several motors and a manual tranny, so I would say my mechanical skill level is above average, based on the luck I have had after the rebuild/work was done.

How bad is this thing with all the FI crap etc?

Thanks for the input!

 

[NoEcm]

You should be able to do the job yourself.

Cracked head(s) are pretty rare in the 5.7L Vortecs especially when the engine has not been overheated.

If the Intake Manifold Gaskets were not the "Fel-Pro MS98000T PermaDryPlus" or equivalent, this could be the cause of your leak again.

Once you starting taking the engine apart, when you get down to lower intake manifold gasket, you can always stop there if the gasket(s) are bad. The new no leak gaskets are metal and rubber. The old stlye gaskets are hard plastic.

Good luck

 

[shreksbrother]

Piggybacking on NoEcm's comments, if you get down to removing the heads, take them to a reputable machine shop. They'll be able to check the heads for cracks. If you find none, replace the gaskets. It's worth the extra money to get the heads checked because if they're good, you'll save the money for new ones.
As far as the pain with FI, it's just extra wiring and fuel rails to get out of your way. With your experience on rebuilding motors, not only should you have no problem removing/replacing the heads, you should enjoy the extra room in our engine bays (as opposed to MGs, Triumphs, etc) to work!
Be sure to do it as soon as possible, running the motor with anti-freeze in the oil will wear down your engine that much quicker, and before you know it you'll be performing an entire motor swap.
Good luck with it!

 

[Deezltahoe]

You should do a compression leakdown test first. that will tell you if its the heads at all. if they bleed down its a head gasket or head if they don't then its the intake. the other thing this will save you from having to do both head if you don't want. you can find the side that is bad and just do that side.

I think that price is steep. You can buy a set of GM vortex heads ( I think thats the ones this truck comes with ) for 600.00 complete. then you just need a gasket set 200.00 and labor. even getting heads rebuit is usually 150.00 a side.

There over charging.

 

[blk87brd]

If your shop quoted you 2500 to do the top end of your 5.7, take your money and run. When they advised you that the 5.7 has design flaws which cause the heads to crack, they clearly show themselfs to be rip off artists. I have never heard of a 5.7 head that cracked that wasn't either frozen or overheated.
Anyone who can repair a british machine will find no difficulty in doing the top end of the 5.7. You just need the tools found in the average tool box, buy a manual for your year, available in most auto supplies.
It has been suggested (correctly) that you do a leakdown test on each cylinder prior to doing the teardown and/or had the heads checked once they are off.
Here is another way you may find your problem. Drain you raqd and engine of coolant. once you are satisfied you have most of the antifreeze out of the block, refill with water in which you have placed dye (I have used both yellow and green in the past). Pressurize the coolant system to about 20lbs (slightly above the normal rad cap pressure) for half an hour. I've put a tube less tire valve in an old rad cap that has the rubber gasket and spring removed. You also have to block the overflow. The dye will leak out and give you an idea of where the leak is when you start taking it apart. They used to make a dye that florisis? under ultra violet but I haven't seen it advertised recently. Your auto parts people may know of a product that does. It will define the leak area and show any cracks you might have.
If you can't do a leak down or the dye, then have your heads magnafluxed before puting them back on.
Otherwise it's a good days work or a weekend job.
Good Luck.

 

[99Tahoe-20/20]

Thank you for the responces and the tips. I was thinking I could swing this and be okay. Little intimidated by all that crap on top but most is just plug and go type stuff so it will be unplug and go. Not fun by any means and I would rather spend my time on the "fun" stuff under the hood some place else, but what can you do.

As for the shop, they are one of the best around and I think the issue might be me living in the good old Seattle area where the cost of living is far from low and it creaps into all areas. I called three shops around to get a feel for this and they all said their are issues with the heads on these motors and that a RR of the both sides will run you about 2500-3000 with tax. Just all labor for the most part!

Geuss I will add it to the to do list and keep driving the old reliabel to work for a while longer (84 F150 with 230k on it)Thanks again!

 

[NoEcm]

Thank you for the responces and the tips. I was thinking I could swing this and be okay. Little intimidated by all that crap on top but most is just plug and go type stuff so it will be unplug and go. Not fun by any means and I would rather spend my time on the "fun" stuff under the hood some place else, but what can you do.

As for the shop, they are one of the best around and I think the issue might be me living in the good old Seattle area where the cost of living is far from low and it creaps into all areas. I called three shops around to get a feel for this and they all said their are issues with the heads on these motors and that a RR of the both sides will run you about 2500-3000 with tax. Just all labor for the most part!

Geuss I will add it to the to do list and keep driving the old reliabel to work for a while longer (84 F150 with 230k on it)Thanks again!

Like all cars, OBS Vortecs do have their own inherent issues but cracked heads and head gaskets are not one of them.

 

[blk87brd]

Just so you know, I live in British Columbia, where labour costs are considerably higher than Seattle. I called two reputable shops and priced out what it would cost to re and re both heads on a 5.7. One was 1950 + taxes and the othe 2100 + taxes. Both quoted 10 hours labour plus fluids. Labour averages 70/hr.
I spoke to a number of repair shops and none (I repeat) none have heard of any vortex head cracks without a history of freezing or over heating. I went to several Chev forums and can't find any head crack concerns.
However, you could easily pick up a pair of good heads from an auto wreckers for far less and due the work yourself, if you find you need heads. My quess is you don't. I'd buy or borrow a leakdown tester, do the dye test and see if I could figure out what seems to be the probelm before I picked up a wrench. With pressure in the rad and a stethoscope, you may very well be able to hear where the pressure is escaping. If you aren't driving it it gives you time to find aq reasonable answer.
Let us know how it turns out.

 

[99Tahoe-20/20]

Oh I deff will do more diagnosis on my end to to ensure I am not chasing my tail. Interesting on the heads. I too thought this a odd thing with cast iron heads. Aluminum and blown head gaskets, sure, but not cast. We will see and I will keep you posted.

The shop did say there was exhaust gasses in the coolant so my geuss is at least the Head gaskets are blown on one side or another. Leak down should show this though.

Thanks again!!

 

[NoEcm]

The shop did say there was exhaust gasses in the coolant so my geuss is at least the Head gaskets are blown on one side or another. Leak down should show this though. Thanks again!!

Funny thing is the OBS Vortecs are not known for blown head gaskets either.

 

[blk87brd]

I think I would question anything the shop had told me after I was comfortable that the story on these things having design flaws was not true. I would set about defining the problem in the systematic techniques offered in these posts. The shop may very well be correct, but I would want to prove it to myself before I ran with it. Although they are not known for it, it still is a possibility and as you say the leak down test will let you know that exhaust is getting to the cooling system, however, it could be from a blown head gasket or from a cracked head or from a cracked block. I would go from the leakdown to the dye so when I start tearing it apart the dye will tell me where to look.

 

[mygreen98]

i had the same problem on my 98. it did crack both heads, no overheat, no freeze either. truck would go thru a gallon every month. drove it like that for awhile, then decided to rip it apart. found cracks between the exhaust and intake valves on both heads. WOW, didnt expect to see that. I owned my own repair shop for 20 years, rarely saw cracked chevy heads, but it does happen. didnt expect to see it on mine , with no overheat/freeze issues. ordered 2 new ones from gm parts direct online,(cheapest i could find) put them on, perfect since then. not hard to do.