706 chevy heads crack

The crack location can be found in any of the five cylinder heads oil drains. Hopefully its a head gasket and not a cracked head but the signs dont. Also, there looks like something hit the top of the chamber between the intakeexhaust valves, like theres a little piece of it missing, though it doesnt go as far as to. But he was going to check his 2006 silverado to see if he has the 706 heads. L33 engine in sons turbo truck has a cracked block. This can be seen as a clean or shiny area, on an otherwise stained surface 1. No 243s or 799 have the casting defect that ive heard, it was pretty isolated to the castech only 706s on gen iii 4. So i just got back from visiting 3 different dealers. Hey guys, i just joined this forum because i am looking to buy a silveradosierra soon but still have a couple questions. Discussion in the hokey ass message board started by 1946chrysler, jan, 2009.

So, even a brand new car can experience cylinder head cracking. This article will discuss cracked cylinder heads, weak valve lifters, worn valve seals, and positive crankcase ventilation pcv fouling. The second was familiar and said they havent seen many bad heads. Cathedral port 243799 are the best flowing gm production heads for. Oct 24, 2011 stock ls heads including the 706 heads on our lm7 5. Equipped with the 706 head upgrade and mild comp 265 cam, the 6. Jul 04, 2006 vortec heads were designed based on the 1996 caprice 9c1impala ss lt1 castiron head castings. The complete cylinder head guide for chevy small block engines. Major cracks can cause severe damage to the cylinders of the engine. Product was successfully added to your shopping cart.

To enjoy a quick replacement and highstrength components, install an aftermarket chevrolet silverado cylinder head from autozones premium selection. When servicing or rebuilding a gm ls engine which includes the lq series, cast iron or aluminum blocks. Back in the 6070s this was a problem because cast iron and aluminum had different expansion rates. Cylinder head cracking overheating is the most common cause. New 862 or 706 casting cores are cncported and machined to specifications dictated by extensive research and testing. You need to pull the valve covers and look for the battery looking symbol. Chevy cylinder head identification small block casting. Ive read a lot about these heads, but my thoughts are inconclusive. If the cylinder head fails, it will lead to the engine and by extension the vehicle breaking down. Ls ls1 ls2 ls3 ls6 ls7 lsx 706 cylinder heads set 4. Plan a, get the heads pressure tested to see if they leak coolant, decide based. Vortec heads were designed based on the 1996 caprice 9c1impala ss lt1 castiron head castings. To test our daily driver head and cam package, we selected a 6.

Chevrolet vortec cylinder heads fast burn combustion chamber and highvelocity ports combine to produce big horsepower. Nearly half of the 706 and 862 castings are cracked around the three head bolt bosses in the middle of the head. In terms of peak flow, the 241 heads offered 242 cfm at 0. Pontiacchevy aluminum, 91cc chamber large rectangle port. How to check aluminum heads for cracks it still runs. Gm casting defect with ls heads don terrills speedtalk. Thanks to the added compression from the 706 heads, torque production improved through the entire rev range. The constant change in temperature causes cracks to form in aluminum heads. Coolant leaking into cylinders 706 casting gm truck. Small block chevy ls cylinder heads by casting number. We dont try to fix the heads at all as its quicker to get replacement heads and get the vehicle back in service either the same day or overnight. Chevy truck forum silverado sierra gmc truck forums. Chevrolet silverado 1500 engine cylinder head getting the job done is easy in your hefty chevy silverado, but even that ample torque doesnt go far with a worn cylinder head. Stay away from 706 heads, some of the early ones have a bad casting that cause them to crack and leak coolant.

This is a relatively common problem you may discover on gm. General motors estimated that through 2005, more than 90. That was cast techs mark the name of the foundry was something like cast tech my 02 has over 200,000 miles on it with cast tech heads with no issue. Americas favorite highperformance cast iron small block cylinder heads offer big power and bigger value. Time and moneysaving tips from technicians automotive service. Im trying to narrow down my solution to my problem and wanted some opinions before i throw more money at this thing. I seen some heads online that are 862 but dont have no logo on them. Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. It takes a fully ported fuelie head to eclipse those flow numbers. Well, i bought a used pair of vortec heads and theres a tiny crack at the edge of the combustion chamber, its just big enough that i can barely hook my finger nail in it. The only difference is the water jacket revision so these heads could be used on conventionallycooled small blocks. Gm has issued a tsb for the issue, but provides no help funding the millions of necessary repairs. Sep 24, 2015 new 862 or 706 casting cores are cncported and machined to specifications dictated by extensive research and testing.

There are 2 other sets of 706 s that are not affected. Allied motor parts has over 150 years of experience of remanufacturing. Small block chevy heads have been manufactured since 1955, and have been used in high performance applications as soon as the first one rolled off the assembly line. So far i know they will raise my compression, from some reading it will be good low end tq but. I have been searching for a few days and it seem as if no one has the answer to the question about only castech making the 706 head. I recently found out i have the dreaded cracked heads by castech. Cracking causes the head to lose pressure, resulting in lost power for your vehicle. I wouldnt even bother with it just pull the heads off and check the head for cracks or a head gasket. Does the product blue devil really work for fixing head. The universal fit called for meant the original sr heads had small valves, but these heads were so well received that they felt justified in producing the sr. Our compression lessons chart illustrates how the compression. Every thing ive read says the 862 on the l33 are the same as 706 heads. When performing your own check for cracks, you need a method of testing that does not use expensive equipment and works with a nonmagnetic metal. Some of the propaganda from chevy states that the heads on the l33 are ls6 units with bigger valves and bigger ports.

This specific guide is for the chevy lm7 ls truck engine. Gm has issued a tsb for the issue, but provides no. The real problem with these heads has to do with the cracks by the oil drain holes. The 1996 lt1 castiron head was the highestflowing lt1 head used by gm. Ok i was reading everyones blaming the 706 castech heads there saying they go out at 80,000 miles mine has 174,000 mile no coolant leaks. Nov 27, 2017 what we had planned to test was a set of stock 4. The cylinder head included in this listing will fit the vehicles listed below. Iv decided to trade it and and im trying to avoid having the same problem again with my new truck. Silverado engine cylinder heads best engine cylinder. The first service writer was no help at all as he hadnt heard of the issue.

Cylinder heads that are identified with the number 706 are potentially plagued with porosity and cracking problems. Dec 05, 2008 the crack location can be found in any of the five cylinder heads oil drains. Fiftyfive years of manufacturing have left us with an endless number of different cylinder heads for the sbc engines. Use these casting numbers to identify the heads you have. Stock ls heads including the 706 heads on our lm7 5. Surprising hp numbers from our stock ls cylinder head test. Lq4, ls6 cam, 706 heads, 317 heads, junk yard dog, and. Allied motor parts sells cnc ported lm4lm7 706862 cyl heads. Chevy cylinder head identification small block casting numbers, big block cylinder head, camel back heads, double hump heads. Each set of heads is milled and assembled to the owners specifications and utilizes stainlesssteel valves. After adding coolant the second time i knew something was wrong.

The most common reason for cylinder head failure is overheating caused by coolant. So, when replacing either the cylinder head or the head gasket. Apparently the castech heads have a tendency to crack, allowing coolant to mix into the oil. In this video i show an example of cylinder head on a 5. The symptoms of cylinder head failure are varied it is important that drivers are able to recognise them as quickly as possible so any damage can be limited. So far i know they will raise my compression, from some reading it will be good low end tq but not quiet up top. Customer requsted repair by the way, they had bought this stuff and wanted me to do the work.

Im planning on changing my heads with some non castech heads because i currently have the castech 706 and are cracked. There are 2 other sets of 706s that are not affected. The local chevy gmc dealer keeps a supply of replacement heads in stock. Chevy performance sbc cast iron vortec cylinder heads jegs. So far i have a buddy with some 862 heads hes gonna let me have for 80 bucks, not bad. Typical 346cid output with daily drivable hrs is 440480rwhp sae.

I am wondering in terms of flow,compression,ect i will be using them on a 5. Apr 04, 2019 the real problem with these heads has to do with the cracks by the oil drain holes. Dec 12, 2014 so i just got back from visiting 3 different dealers. I found a couple cracks in between a couple of my valve seats. Vortec heads can be mildly ported for additional performance and milled up to. Gms 706 vortec heads are the cheapest and most effective heads you can use for your 5. This is a discussion on 706 heads on 01 ls1 within the internal engine forums, part of the lsx technical help section category.

Read on to see what attention your silverado may need and how you can protect it from damage. It does not indicate the 706 marking in the document. While i have the heads off though im thinking of throwing in a 220r cam and z06 timing chain might as well since i dont have the service records. Does the product blue devil really work for fixing head andor head gasket issue. These heads outflowed the corvettefbody aluminum lt1 heads. Just wondering if anyone has played around with this before. A guide to vortec vs oe small block chevy heads by bobby kimbrough march 03, 2010 small block chevy heads have been manufactured since 1955, and have been used in high performance applications as soon as the first one rolled off the assembly line.