5.0 Cracked Heads

[beauhymel]

I had this posted in the Clasic Truck section. This on an extra,hunting,fishing truck.

 

I have a 1996 GMC 1500 with the 5.0 it seems that my wife overheated my truck until it would go no more. After the truck was overheated the known problems are, leaking water pump very very rough idle. It seems to be running on 3-4 cylinders, not enough power to move truck. My question is what to look for? The oil is still clean and looks good antifreeze gone. I think I have at least a blown head gasket, maybe warped/cracked head, or block. I need to know where to look for cracks and any other Ideas.

 

Well I removed the heads and it is worse than I expected. Both heads have cracks. Should I dig more or is this something to expect with an overheated 305. Now I need to go over my options, junk-yard, rebuilt, or new heads.

 

NAPA replacement=$324, AutoZone replacement=$267, Cylinder Heads International=$175

 

Has anyone used Cylinder Heads International? The website claims to sell 1200 heads/month. Their price seems good, but I would like some feedback from someone that has used them. I checked the block and it is flat. I also checked all visiable surfaces and that looks good. Does this block have any week spots that I should try to check more closely. The cylinders all look good. (as much as I can check with the pistons still in there)Thanks again.

[Nytemare]

5.0 Vortec is a good engine...Other than your cracked heads I would say your ok.

I would say that your cheapest solution would be a junkyard engine....however, it may be on its last legs too.

On the other hand, you may be able to get a set of heads from a junkyard for little or nothing...its not like they're a performance or highly sought after part. I just did a search and have found heads as low as 100 bucks a pair. Checked and surfaced, your looking at 300 bucks total. Buy a complete top end kit and re-lap the valves and use which ever valves look best out of your heads or the ones you get and your Golden man.

 

To do a full rebuild you should be in it no more than $2000 bucks, with new heads...it seems like you have an idea whats going on, so I assume you have no trouble doing this yourself.

[beauhymel]

Thanks for the quick reply. The only problem that I have with sinking 2G into the engine is that after I will have a 2G truck. I am leaning toward the rebuilt heads ($175ea). I just want to know if the vortec 305 block had any know weak points to check before going forward. Thanks again.

[Nytemare]

Thanks for the quick reply. The only problem that I have with sinking 2G into the engine is that after I will have a 2G truck. I am leaning toward the rebuilt heads ($175ea). I just want to know if the vortec 305 block had any know weak points to check before going forward. Thanks again.

None that matter for a DD or a fishing truck that I know of.

 

As a racing engine....lots....but you should be fine.

[Westlotorn]

I agree that the 305 was a good workhorse, no real problems other than intake manifold gasket failure that plagues all Vortec family engines. Fel-Pro has the bomb gasket that fixes this MS98000T.

 

Before spending money on heads make sure your rotate your engine and with each piston at the bottom of its travel check the cylinder wall to make sure the overheat did not scuff the pistons and cylinder wall.

 

In over heat the cylinder wall can hit temps that exceed your oil protection and the pistons drag on the cylinder wall. If this happened you will see burned scratches running up and down the cylinder wall, usually on the exhaust side of the cylinder, sometimes on the intake side but never on the front or back of the cylinder wall.

 

If you have piston scuff your only option is to replace or rebuild the engine, it will need to be bored to fix the cylinders.

 

If you need to replace or rebuild the block you might look at a used engine since you are not wishing to spend two grand at this time.

 

If the cylinders look good, replace the heads and move forward with your old block assuming it is less than 150,000 miles. If the old block has high mileage you may wish to start over.

[beauhymel]

Thanks for the replies. I will report back on what direction I take and how everything works out.

[Jsdirt]

The absolute cheapest way out would be to scour your local want-ads or Craigslist for a complete engine. I've seen complete engines go for less than $500 in some cases, if someone is looking to clean their garage out ... or part out a vehicle. It's a bit of work, but will save you a ton of dough.

[beauhymel]

Well, I am going with rebuilt heads from Cylinder Heads International. They hav a 12 month warranty. What gaskets should I use? I am leaning to Felpro, but let me know if something out there is better. Is it neccessary to go with new head bolts? Thanks

[Nytemare]

Well, I am going with rebuilt heads from Cylinder Heads International. They hav a 12 month warranty. What gaskets should I use? I am leaning to Felpro, but let me know if something out there is better. Is it neccessary to go with new head bolts? Thanks

My favorite gaskets for a stock or a little better than stock engine are Felpro Gaskets

 

Its not necessary for new head bolts on a Gen 1 SBC engine, but for 20 bucks for a Felpro set...why chance it.

Get a FEL-PRO Part # HST8510PT6. Those are sever duty perma dry gaskets...and they're 117 bucks for the entire top end set. Thats all the gaskets needed to do a cylinder head job.

[beauhymel]

Well its been quite some time but I finally replaced my heads. Things don't look good. I have a slight knock in the bottom and it is burning oil, I had more damage than I had hoped. I guess I will now either be pulling the motor and doing a complete rebuild, going with a rebuilt short block or trying the junkyard route. If not does anyone know a good supplier of GM short blocks? If I replace the motor with one from a junkyard what problems would I have going from a 5.0 to a 5.7? The Vortec 5.0 seems hard to locate around here. THANKS again.

[Nytemare]

Well its been quite some time but I finally replaced my heads. Things don't look good. I have a slight knock in the bottom and it is burning oil, I had more damage than I had hoped. I guess I will now either be pulling the motor and doing a complete rebuild, going with a rebuilt short block or trying the junkyard route. If not does anyone know a good supplier of GM short blocks? If I replace the motor with one from a junkyard what problems would I have going from a 5.0 to a 5.7? The Vortec 5.0 seems hard to locate around here. THANKS again.

Rebuild it man...get at least some moneys worth out of the heads you just bought.

 

If you wanted to swap out to a 5.7 Though, all you would need to do is get the ECM for the 5.7 and the engine should plug into the same harness. Just make sure that you get the same Fuelinjecton on the replacement as you have on the one your taking out. I'm pretty sure you would have a TBI 5.0L so you have to get a TBI 5.7L

[beauhymel]

Well the saga continues. I deciced that I would pull the motor and rebuild. Due to limited overhead I pulled the intake and heads in the engine bay. When moving the heads I noticed one had no valve stem seals. I replaced the valve stem seals and after some thought I reinstalled on engine. Well the burning oil is gone and have not lost any coolant. The noise I had heard earlier is not in the bottom. The noise now seems to be valvetrain related. I have 3 lifters that I can not seem to set. I have tried tightening until I have drag on push rod and going 1/2 turn (hanes) I have also tryed backing off until tapping (running) and slowly tighting until no tap is noticed (old school). n the three above mentioned cylinders it seems to start missing (valve float)???. Is it possible that when the truck was overheated that the cam/lifter were damaged? I guss next I will be pulling the intake again.

[Nytemare]

Well the saga continues. I deciced that I would pull the motor and rebuild. Due to limited overhead I pulled the intake and heads in the engine bay. When moving the heads I noticed one had no valve stem seals. I replaced the valve stem seals and after some thought I reinstalled on engine. Well the burning oil is gone and have not lost any coolant. The noise I had heard earlier is not in the bottom. The noise now seems to be valvetrain related. I have 3 lifters that I can not seem to set. I have tried tightening until I have drag on push rod and going 1/2 turn (hanes) I have also tryed backing off until tapping (running) and slowly tighting until no tap is noticed (old school). n the three above mentioned cylinders it seems to start missing (valve float)???. Is it possible that when the truck was overheated that the cam/lifter were damaged? I guss next I will be pulling the intake again.

Just do a rebuild man...no use half assing something together, than having it quit and leaving you stranded on the side of the road.

[gmtech4]

i put in a gm rebuild for a guy at the dealer in a POS truck ,he was a PITA after but people do these things lol

 

aaaahhhhhhh,all I got is holy shit and ummmmm............short block it,flush oil cooler too,change oil & filter at 1500 miles or after 1st hunting season lol