Customer States: My 5.3L is using coolant!

Customer States: My 5.3L is using coolant, so we get to the bottom of the coolant issues.
Powellmachineinc.com

[@Brad.wilson1111]

Super common issue with a 5.3l. Coolant consumption with no external leak. Also we see them often only leak at certain temperatures. Keep in mind you are pumping 38 psi in the head. A shop only presurizes to 15 or 16 psi. I really appreciate you showing us where to look on the heads. This is very helpful.

[@powellmachineinc3179]

TYVM

[@arturozarate1752]

Agreed. The system is pressure tested to the rate of the cap, and maybe a few pounds more, but never as high as 38psi. I'm not trying to stir anything up. I clearly see the bubbles that identify the leak, but where's the coolant? A Ford dealer I worked for around 2010ish also sold Hyundai. I had a Sante Fe come in using up to a gallon of coolant between oil changes(4k to 5k interval). Pressure tested and never lost more than a lb over night. I finally had to tear it down. The #3 sleeve was low by 0.003" compared to the others @ zero deck. I chose to tear it down after removing the spark plugs and seeing the #3 plug differed in color. The piston was clean. Steam cleaned by the coolant and the combustion process. The sleeve was loose. The small amount leaking past the gasket was never seen out of the tailpipe, but the clean piston was the identifier. In 25 years that's the only Hoodini act I've ever seen coolant make. Through that small of a crack...it's possible that it could steam out and mix with crankcase vapors. This is a good one to look put for. Thanks for the video.

[@rollandsicard1628]

Very interesting. You have come to the top of my list of very good engine machine shops. Quality is number one which will be followed by folks knocking at your door to do business.

[@powellmachineinc3179]

Thank you very much!

[@FUNKYTEE540]

Had this exact same thing happen on 706 heads. Coolant slowly creeping into the oil pan over time created an epic sludge problem. Thanks for the videos! Keep em coming.

[@benrossbach6501]

Heard of the problem but nice to have such a great video available. As always thanks

[@powellmachineinc3179]

Ty for watching!

[@Carcrafter7165]

I’m so glad I watched this video. I had no idea about the 706 heads. I had a 2006 Chevy Avalanche with a 5.3 with 706 heads but I had no issue with them.

[@powellmachineinc3179]

Good deal

[@srduty9389]

Thanks for the info. I've been wondering about those cracks between the valve seats. I appreciate you sharing your knowledge and look forward to the next video.

[@powellmachineinc3179]

Glad to help

[@strokermaverick]

Being, I'm a Ford guy, I don't have to worry about that. I, have my own list.😀 Thank you, for the upload!

[@powellmachineinc3179]

Right on!

[@kwiz8848]

Cam phasers #1 😂

[@rodx5571]

i pulled valve covers on a 5.3 pickup and immediately saw leaking head bolts. The heads tend to oil stain, and i saw the "steam cleaned" spots around the head bolts. It also looked like the orange drink Tang paste in the valve cover. Customer declined repairs. Sold him an engine 4 months later.

[@hotrodgmc68]

I have a 2003 Sierra that has been plagued with two sets of cracked heads. The original set were 706’s that lasted until 2017. The second set was a CNC ported pair of GM castings done by PRC. The casting numbers were machined off for their logo but they did not have the Castec logo in the casting. Those lasted three years before I noticed coolant going missing again. Both sets of heads cracked on the same holes and made a hell of a sludge mess throughout the engine. Just for grins, here’s the GM TSB about the issue- #06-06-01-019B

[@powellmachineinc3179]

Sorry to hear that, we offer cnc work, we also have aftermarket castings that are much nicer

[@lancasterjim2441]

I see this issue on different applications from time to time. Look closely shown in your video you can see the un even contact patch on the head bolt boss they are both bias towards the crack . The bosses need spot faced so the head bolt torques down evenly

[@michaelkrumm1198]

My 2000 4.8 L cracked in both center headbolts I used a half a bottle of Bars Leak and it lasted another 7 years then I sold it. I did have to circulate Vinager through the heater core to restore flow through it. Now I don't recommend doing this to others but it worked out for me.

[@jefffrayer8238]

Bars Leak is known for plugging up stuff. I've had excellent results with AlumAseal powder that seals only leaks quickly, permanently.

[@MarineGrunt]

Its hard to believe that didnt show up during either of off site pressure tests . It should have , hot or cold ....although even the biggest leak was what Id call minor . More than enough to cause concern though . I think the other shops just rushed him out the door without being thorough .

[@powellmachineinc3179]

This just proves a real pressure test was never actually done...

[@MarineGrunt]

@@powellmachineinc3179 Or....they did what I call a radiator pressure test . That's a lot less work than a leak down test that gives you real results .

[@MarineGrunt]

I'm sure glad I watched that video again . The guy got shorted by the other shops , but a leak down test probably would not have caught that anyway . Good thing he was staying on top of his coolant usage .

[@2nickles647]

From what Daniel says. You need to pull the valve cover and clean the head bolts areas and then pressure test. The so called GM super qualified ASE did a professional testing and no leaks. Anybody is called a Technician these day's.

[@bluecollarhotrods9781]

I generally avoid 706s, they're such a crapshoot. And no one locally to me has a fool proof method for making sure they are 100% crack free. I have a set, they visually "look" OK. But, I'll be honest - I'm afraid to use them. The more I think about it... I'm going to turn them in for cores.

[@powellmachineinc3179]

Definitely, pressure test is the only real way to know

[@bluecollarhotrods9781]

@@powellmachineinc3179 the local to me shops I tried didn't have that capability... which is insane to me. Most late model stuff has aluminum heads. One even told me, "can't magnaflux them because they're aluminum" Cool, I asked for them to pressure tested. Lesson learned, never go back.

[@powellmachineinc3179]

@bluecollarhotrods9781 they actually make suff called "Dye penatrant " that is a 2 part arasol we can use on aluminum, any shop should have that

[@bluecollarhotrods9781]

@@powellmachineinc3179 you would think, but this place in particular acted like they didn't want my business. I saw LS blocks and heads scattered around, so it's not like they don't work on them.

[@melissatuason2395]

When my husband was a technician, he did 2 tests for water loss or usage. 1) Pressure test on the coolant side at 22-25psi.2) cylinder pressure tests in each cylinder & see of the coolant in the rad bubbles up he says. The problem will show up one way or the other. 3) he listens to the exhaust pipe for air bleed on the internal leaks. However water loss can be as simple as a radiator when it loses its spring pressure causing water to be expelled prematurely through time. He thought he he would share his past experience.

[@jamesbergman4917]

GM issued a recall for those early "battery" symbol 706 heads.

[@powellmachineinc3179]

Did know that

[@dalesmith561]

I had the same problem at @ 95,000 miles, but with 242 heads. I replaced mine with 799 heads, they don't seem to have the problem with cracking. I also have another set of 799 heads, if anyone is looking for a set.

[@hotpuppy1]

Hmm. It seems like most small cracks like that ought to show. Maybe too small to see visually until it heats up to operating temp? I have an old OHC Pontiac 6 with a cracked block (inch long external crack) that seeps a little but not enough to matter in the radiator level. Hardly worth messing with. If it was internal to leak into the oil, I'd fix it. Junked a 350 Chevy block that had a crack in the valley. Wasted my money on that core and it looked OK on the outside and ran OK. Was just going to do a hot tank and re-ring job on it with a new cam.

[@kwiz8848]

Currently rebuilding a l33 for this same issue. 250,000 miles 799 heads non castech. I noticed coolant loss could never locate it until one day the with engine at operating temperature I could hear a loud hissing coming from under the driver side valve cover. I’ve always changed oil religiously, once it was torn apart found sludge in the entire engine. Luckily no damage to bearings caught it just in time.

[@MichaelScudder72]

They probably pressure tested the cooling system VIA the radiator cap and never pulled the heads at all.

[@brianed1258]

Love your work mate 👏

[@mikelawler2278]

And I got 706s on my 5.3 when I got it. I'll be sure to look good when I start working with them.

[@HarleySLA]

I had the same thing happened to me on my Honda Civic with the D16. Bought a junkyard special, I really wanted to get it rebuilt right- however it was stuck at work.... So, due to time constraints I slapped a few seals in it and dropped her in. 10k miles or so go by and it began eating coolant, head gasket is torched. I hate it, but can't cry over spilt milk. Maybe one day ill get a proper engine in that turd, but prolly not. I love that one ton go kart though, I really do. Its a turd but it's my turd.

[@powellmachineinc3179]

Yep, it happens

[@Jon-q5y]

Thanks that will help

[@powellmachineinc3179]

Welcome

[@406nitrocamaro]

Good find

[@powellmachineinc3179]

It's pretty common

[@Mdc869]

I would have put a bottle of stop leak in it and rolled on....lol

[@prvtnewbie]

I was under the impression that 706 heads had different manufacturers, Castech manufactured were known for cracking but the other manufactured heads didn't have that issue? I have a set of non-Castech 706 heads that i was going to use but was curious if any can confirm or deny the Internet 706 info? Being a shade tree mechanic, i don't have any experience with heads so wanted to see what others thought. Also, I am impressed how clean the shop is and I realize its time to clean up my garage. 😃

[@larryssnova76]

2nd time I watched this video I hope when he did the leak down he pulled the rocker arms off because if he didn’t it makes it really hard to keep the engine from rolling over especially on that Because those valves were tight

[@powellmachineinc3179]

This video has nothing to do with leakdown, this is a cracked head /coolant leak video

[@robertchall8576]

Thats good to know.

[@budlanctot3060]

Two comments/questions: 1) Did you say you pressure check the heads at 38psi? Why so much, when the cooling system sees less than 20psi? 2) Regarding that bolt hole area which was leaking, why does the spot-facing "look funny". It looks like the underside of the bolt head is not contacting the spot-face evenly, as if the spot-face is not square to the drilled hole. Maybe its just an optical illusion, but that's what it looked like to me.

[@NBSV1]

When it’s the whole cooling system you don’t want to go much over cap pressure or you risk damaging the radiator or other more fragile parts. When it’s just the head you can go higher on the pressure so it’s easier to see the leak. At 20psi it’d likely still leak, but be harder to find.

[@AlxJrz401]

Thanks for the upload! great info!!!

[@HeadFlowInc]

This is why I stopped working on 706 heads; not worth the chance when I’ve never seen the 862 head crack.

[@powellmachineinc3179]

Yeah, this is the first time I have ever had a issue and we do hundreds a year. But...moving forward I think if customer supplies we aren't going to warranty them

[@Yelladog78]

Man I really thought GM nailed it with the LS engines but I'm thinking the 5.3 is an engine I'll just keep clear of

[@skylinefever]

Some casting numbers are so bad, rebuilders refuse to take them. If you deal with a Jeep 4.0, nobody will accept your regular 331 head. If it isn't a 331 TUPY, parts companies will sell you a rebuilt 331 TUPY or a new aftermarket casting. They don't need the hassle of replacing something under warranty.

[@powellmachineinc3179]

Yep, we see a lot of 4.0 jeeps

[@myfastcars]

OUTSTANDING INFORMATION...

[@popswrench2]

"706" then i looked 😅😅😅😅 not the 706 i am use to 😂😂

[@daledavies2334]

Well known problem. Gets boiled out of the oil.

[@powellmachineinc3179]

Yeah, definitely for shop's, not so much for the public.

[@eb972]

Master GM tech. lol.

[@powellmachineinc3179]

Exactly

[@thisisyourcaptainspeaking2259]

Good to know, thanks!

[@powellmachineinc3179]

Happy to help!

[@JeremiahSchaefer-tb6lw]

Even if it's not "visible" i like to run it to operating temp then pull a valve cover(s).... ta-da

[@powellmachineinc3179]

Yep

[@robertwest3093]

You would think that after all these years of casting blocks and cylinder heads that GM would know to put more material in certain areas.

[@michaelraddish7898]

Mine leaked same spot,my mechanic knew what was wrong as soon as i told him i was losing anti freeze. New heads 1400 later.

[@rossryder944]

So if there is no water/coolant in the oil, then where did the lost couple of quarts per 1,000 miles go?

[@powellmachineinc3179]

Evaporation

[@kwiz8848]

Through the pcv and out the exhaust

[@rossryder944]

@@kwiz8848 Actually, that's where the oil goes. One of a few frustrations of LS life.

[@travisbooth7106]

Have seen them welded

[@powellmachineinc3179]

Yes

[@michaeledge8905]

Yep had the same problem in my 2000. B/O cracked first gen heads

[@powellmachineinc3179]

Definitely

[@Anthony-nw5zv]

I had no idea.

[@powellmachineinc3179]

Yeah, super common

[@beeasy4360]

Definitely helps me on where to look for a crack I got a supposed to be 5.3 out of a 2004 Escalade with 706 cathedral port heads ! Got it all together keep blowing antifreeze out of radiator so I tested it with and had combustion gas in coolant go figure. So I believe it’s a lm7 how do I know for sure so I don’t get wrong parts ?

[@powellmachineinc3179]

That engine should have had 799s

[@beeasy4360]

@@powellmachineinc3179 the guy told me it was out of a 2004 Escalade could it have been a Tahoe or something else is a iron block 24 tooth reluctor but don’t always count on what some says how do I make for sure with taking engine completely apart ?

[@timjones4554]

Could use the pioneer ceramic seal in this situation with the aluminum heads and be good?

[@powellmachineinc3179]

Most likely it would work fine

[@mikebeale9242]

Would that cause it to look like real bad condensation under the valve cover…damn I wish I had seen this video a long time ago.

[@powellmachineinc3179]

Yes, that is exactly what it will do

[@CoroPlanesLLC]

I am confused. You said there was no coolant in the oil, but it was leaking 1 - 2 quarts per 1000 miles through a crack next to the head bolt... Where was the coolant going? I would think it would have to go back to the sump, and there would be evidence in the oil. Did the shop just miss it, or am I misunderstanding where that crack was and where the coolant would have to drain to?

[@powellmachineinc3179]

Evaporation

[@2nickles647]

You will see a gray type sludge on the oil filler cap or tube areas.

[@rogersibilsky3786]

Using water at such a slow rate/small amount...it would of burned off in the oil.

[@powellmachineinc3179]

That's exactly what it was doing

[@frizzellracing]

I’m not a LS guy, so curious. Are those heads now just scrap or is that repairable

[@powellmachineinc3179]

Junk

[@timothybayliss6680]

A set of 706 or 862 heads is almost free. You could probably get a set at the wreckers for $100. Oven cleaner, pressure washer and $200 on new valve springs and a gasket set and you are golden. Even taking them to a machine shop might be a waste of your time.

[@kricketscreations4887]

What do you think about welding where they cracked or know some been done will it hold up or is it cause more of a problem

[@powellmachineinc3179]

Definitely, you can weld them

[@bobmutchseo]

So how did you work it all out with the customer? Is this a motor you sold to them and you covered all this work.

[@joeyelliott-bh3yb]

your the man how can i get ahold of you 2 ask u a question?

[@nextgen1939]

I have seen a lot of the 706 heads cracked there.

[@powellmachineinc3179]

Definitely

[@user-no8mv4tw8j]

Wait so 706 is referring to the application of the engine? Like it’s got an iron head and is the truck version? Or am I completely off on that assumption?

[@raydavis7241]

Was the oil getting coolant in it?

[@jimmyford796]

I never knew that. Wouldn’t he have coolant in the oil?

[@powellmachineinc3179]

Evaporation

[@sfopaladin2661]

I might add Mr Powell, the cause of the cracks might be the heads heating up with overtemp coolant. The driver never notices and just keeps refilling the reservoir. One clue is the same area cracks develop on most of the heads you see. Might be a cause. 🤔

[@retired-pipefitter]

Wouldn’t that have leaked coolant into the oil? Seems likely

[@NBSV1]

It would have been a slow leak. If they drove it enough to get the oil good and hot it would evaporate the coolant out of it. Generally takes a pretty big leak, or short trips to make the oil milky.

[@jalbarado1]

Every 706 is cracked or will eventually... junk...

[@MsKatjie]

Experience talking.

[@powellmachineinc3179]

Ty

[@FixItStupid]

TY Good Tech To Know

[@RR-bt5xv]

maybe at 15 psi the leak is to small to show on a normal gauge. also who pulls the valve covers to look for a leak when gauge is not really showing a drop in pressure its possible you missed it also and sent the heads out like that

[@bobhudson6659]

A couple of things. If the heads are known to crack, then a higher pressure test, purely on the motor, blanking off the heater core and radiator could be done by anyone who knows what they are doing, when they find out about the problems with these heads. 2nd thing. By your second comment about Daniel possibly missing the cracks when they rebuilt the motor, including the heads, you are accusing him of lying. Daniel said they pressure tested the heads before assembly. He, as an engine reconditioner of many years standing, knows very well of the cracking issue and would carefully check each and every head that comes through his workshop. How would you like someone, in a public forum, accuse you of lying. Daniel is not one to get in your face, not easily. But don't push your luck. Hope you can do all the work yourself because if you take your engine to any engine builder and they find out it was you who questioned Daniel's credibility, you are out in the cold - no-one will touch you. Retired mechanic/machinist in Australia.

[@RR-bt5xv]

@@bobhudson6659 not sure what your smoking down under but keep it there

[@2nickles647]

The crack may not show itself during the inspection or rebuild. I think over time they start cracking after a bunch of head cycles.