Carbon Buildup and Stuck Valves

[br-549]

Greetings, I'm a newbie here so be patient with me. We own a 1949 Flxible bus with a GMC 401. I posted photos awhile ago. The bus has been sitting for 25 ++ years in a barn and was stuck when we bought it a few months ago, We just tried to make our 1st trip- approx 450 mile to the FLX rally in Loudonville OH this past weekend. In Venna WV, we stopped to spend the night. The next morning the bus had a dead miss. LONG story but i was able to determine i had a stuck intake valve on number 1 cyl.
When we pulled the head the engine was VERY clean except for the intake chambers? I had to drive the valve out of the head but after we cleaned the valve guide and and valve stem they where fine. No warp, no wear. So, what caused this? We completely cleaned the head and made it home using the old gaskets and such. Now i realize several things- the timing was to high, the valve where adj. to tight, the points where a little off, but was this enough to cause excesive carbon? We are now running Marvel mystery oil in the tank and crankcase as well as lead additive in the gas. I am going to need head gaskets at some point i guess just because i reused them. Help me here- what are your thoughts? Thanks in advance for your input.

ja

[Charon]

Could be pulling oil in the pcv system. But a stuck valve on a running engine. Carbon would not do that. . So a rig that has set 25 years. How well did you clean the fuel system? A black tar residue could be in a poorly cleaned tank. That will dissolve into the fuel. And it will stick valves like crazy. And if it had copper head gaskets. Use those wuth no worries.

[br-549]

Thanks for your reply. I drained both fuel tanks of approx 40 gals of very stale old fuel before we attempted to start the bus. I did not flush the tanks. It has 3 fuel filters, all have been changed. We have prob run approx. 100 gallons + thru it at this point. Both taks are full at this time but if you feel it best that i drain and clean them , i will.

I have not noted any oil in the PVC filter element. I have not replaced it but do have one on order. This engine looks brand new inside- absolutely NO internal wear. The inside of the intake chambers where the only thing that looked bad. I will attempt to attach a photo.

We know the complete history of this bus and feel certain the engine has less than 20,000 miles.

I appreciate the input! Jerry

[br-549]

I just added an additional photo in my album of the cyl head removed and the valve that was stuck, removed. You can see the build-up in the chamber. This photo also shows how clean this engine was at disassembly. ja

[snazzypig]

Just looked at your album. Really nice looking bus. One of my first jobs was at the Greyhound Depot in Billings Montana in 1965. Some of the smaller bus lines that made stops there were still using that type bus. Beautiful streamlined styling.
Looking at the combustion chambers on the head, maybe the one that was carboned up had weak ignition, or maybe it had to do with the valves out of adjustment?

[TJ's GMC]

Hi there, checked out the album. Nice looking bus. Now onto the engine.

Been sitting for a long time. There's one possible issue. Doesn't matter if the motor has low miles or not....nothing hurts an engine more than sitting for ages. Gaskets dry up....top end dries....things start to rust. And with today's fuel the ethanol does a number in the tank, lines, and carb. Draining the fuel most of the time is not enough, you'll need to pull the tanks and give them a super good flushing. Then take a look inside checking for rust. Then you'll need to blow out the lines and replace the filters. Going through the carb would be a good idea and then fully tuning up the engine. Oil change first thing! Get that black tar out and put some nice high zinc rated oil in that thing. Then remove the valve covers and check/adjust the valves to correct specs. Then clean or replace the points and coil. New cap and rotor never hurt either. Also replace the plugs....now here is the opportune time to check compression! 125 PSI is the spec from a brand spanking new engine. If finding cylinders under 100 PSI I'd say your engine is worn out and burning oil which would be a part of the carbon issue, or you have valve sealing issues.

But as it seems the carbon build up is mainly on the intake ports and valve seats I'd say that the engine was either burning old fuel, or the a/f ratio is way to rich and the engine isn't burning All of it. Or there is excessive blow by through the pcv which would cause carbon build up as well.

Weak valves springs will allow a valve to stick. And a lot of gum and residue will cause that as well. Be careful as you may have some bent push rods.

[Charon]

You don't need zinc. It was added after these engines were designed. It was added because hipo engines needed stronger springs to keep valve float from happening at high rpms . I would run seafoam for now. And check for any residue on your tanks when you get home.

[Charon]

How long did you run it on that dead hole?

[TJ's GMC]

Never hurts to have zinc in the oil. It wasn't put in oil for no reason.

[Charon]

It was put in to help hipo motors. It's levels peaked in the 80's.it's not necessary in v6. I don't advise it's use. And I rebuilt more engines last month that you will probably do in your life. I run Castro syntec 5- 50 I use about 400 gallons per year. It's bought in bulk. And delivered to my tank. And after break in it's All that is run in my or my customers rigs.

[TJ's GMC]

So all the oil companies that recommend zinc for engines are wrong just because You think zinc is not needed? Funny. And 5-50 is not the GM spec for these V6's by the way. I don't care how many engines you've rebuilt. lol Just cause you can rebuild an engine doesn't mean you know them!

[br-549]

We have the bus home now. It ran great the 300+ miles home. Now to answer a few questions. The valve was stuck at start-up on the morning of second day of out trip. I pulled plug wires until i knew the cyl that was missing. I then pulled the plug and watched it fire. Then i checked for compression and it was good so i pulled the valve cover and the valve was stuck in the down position. I tapped it with a brass hammer but it would not return. I then gently used a crows foot in the spring and could push it up but with each revolution it would stick. I ran blaster down the stem but that did not help. So- i was able to hook up with a friend of a friend about 10 miles away you owned a place we could park the bus and work. I removed the push rod on the affected valve and slowly drove it the 10 miles. We removed the cyl head cleaned all the chambers and parts, checked all the valves and push rods for warp. A gasket set was not available so we reused the head gasket and made new intake gaskets.

Now, when the bus was brought out of storage- the oil and filter where changes- plugs replaced- points- cond- cap- rotor- wires- fuel filters (3) where replace- fuel tanks where drained but not flushed. I think that is where i missed the boat. I did change the last in line fuel filter the 2nd time after driving the 1st 100 miles but this afternoon i checked the clear filter and it looks dark. It will be a major job to remove these fuel tanks. I think i will try to flush them first and see what i get out of them.

I believe i can get a steam jenny wand down the filler neck and steam the tanks- what are your thought on this? Thanks for all the help! ja

[Charon]

My goodness child! Go look at the shear. Pressure ratings. All the specs on oil from 1960. Then compare to today's oil. No comparison. Sadly I think I just found kindergarten again.

[Charon]

You can feel the varnish in old gasoline. Stick your fingers in. And wait till it dries. Then touch your fingers together. You will feel a very slight stickiness. When you pull apart. Last year I had a guy stick 4 intake valves on a flat head v8 Ford. I doubt the system had 4 ounces of very goopy tar in the tank. It does not take much.

[Charon]

Also. Just so People know. You won't stick exhaust valves with bad gasoline. Only intake valves. And the tighter the engine the more prone it is. When an old tractor gets rebuilt. I ALWAYS go one size over when I ream the guides. That builds on a lot of protection from bad gasoline the farmers are famous for using.

[TJ's GMC]

My goodness child! Go look at the shear. Pressure ratings. All the specs on oil from 1960. Then compare to today's oil. No comparison. Sadly I think I just found kindergarten again.

Uh huh. Like I had mentioned already....zinc was added for a reason. And now taken away again because new engines have roller cams and rockers. But you didn't answer my question as to why oil companies like Amsoil for instance recommend zinc oil for flat tappet engines. It's still them against yourself.

[Charon]

Do some research child!

[Charon]

Talk with your rep.

[TJ's GMC]

Do some research child!

I have old man. lol

[Charon]

Your a clown. And I am done child.

[Charon]

Since I am doing a set of heads now. For a Customer. I am leaving you to you binky.

[TJ's GMC]

Your a clown. And I am done child.

Never have I denied that! haha But you make a good one yourself sometimes. :lolsmack2:

[TJ's GMC]

Since I am doing a set of heads now. For a Customer. I am leaving you to you binky.

YOUR* lol

[David R Leifheit]

'tis funny.
From what I can find on Castrol's site, they no longer manufacture "Syntec" it is now called "Edge". They replaced the Zinc with Titanium for better protection at higher heat. Some of the old car forums have been discussing the Zinc levels in Castrol Syntec 5-50....

What I am seeing reading all these oil company sites, and commentaries, is that the government regulations restricting the use of zinc has created the demand for titanium to replace it.

Actually quite interesting reads.

Hemmings has an article on which zinc formulations to look for, but it is out of date (2012). Apparently though Castrol was one of the first to use zinc, and as the amounts allowed were decreased they turned to other additives currently using titanium for the same effect. With the added bonus that apparently the titanium does not need the phosphorous, so the carbon buildup due to phosphorous in the oil isn't happening.

[TJ's GMC]

'tis funny.
From what I can find on Castrol's site, they no longer manufacture "Syntec" it is now called "Edge". They replaced the Zinc with Titanium for better protection at higher heat. Some of the old car forums have been discussing the Zinc levels in Castrol Syntec 5-50....

What I am seeing reading all these oil company sites, and commentaries, is that the government regulations restricting the use of zinc has created the demand for titanium to replace it.

Actually quite interesting reads.

Hemmings has an article on which zinc formulations to look for, but it is out of date (2012). Apparently though Castrol was one of the first to use zinc, and as the amounts allowed were decreased they turned to other additives currently using titanium for the same effect. With the added bonus that apparently the titanium does not need the phosphorous, so the carbon buildup due to phosphorous in the oil isn't happening.

Interesting reading! Amsoil still has high zinc levels in their oil. One for break in purposes and the other for after break in. Even Hemmings oil has a higher zinc level than most. Joe Gibbs and others which i can't remember have zinc. The rotella 15w-40 I run in my 305 has zinc in it.

[GMCDAC]

Yeah interesting about titanium being added to some oils! I have just been using a Rislone zddp additive along with Rotella 15-40 in my '72, Rotella with no additive in my '55 and I recently got a low miles engine for the '70. It was being run with Mobil 1 and a zddp additive so I plan on doing the same thing as it did it's first 30,000 on.

If it was already mentioned, ignore this comment, but from what I understand the primary reason for the EPA regs the feds implemented was that they claimed that the zinc damaged catalytic converters.

DAC

[lizziemeister'sV6]

Getting to what you stated about the cat converter not being able to digest the zinc in the oil that was used in the V6's era - we can also include leaded gas - both plug up cats - lead and zinc are very close to being one of the same - look at babbit bearing material that was used - different ratios of both in different applications of engine usage. Zinc and lead are both excellent as a wear surface additives in oil - bearings surfaces and the bearing journals are cushioned by your oil. :winter:NOT HERE

[TJ's GMC]

Cat converters were a dumb idea to begin with. :banghead:

[ilvracn]

i hate catalytic converters too, but i remember all the smog in the air back in the 70's. i like the clean air better. so i guess i can deal with cat converters

[bigblockv6]

Catalytic converters have come a long way, with hi flow converters today there is really no restriction. The smell of pre converter cars exhaust is annoying, I actually bought some high flow converter I'm going to try on my 68 478M.

[TJ's GMC]

My 292 was Horrible for gas smell in the morning. Oh man! You'd get one heck of a head ache from it. My 305 is awesome! While warming up it doesn't smell to bad at all. :thumbsup:

[bigblockv6]

My 478 puts out a real strong smell when I start it up and run it:ahhhh: but everything else I own is has Catalytic Converters so you tend to get used to the newer cleaner running engines. When the 305 was in the 68 it did real well biannual California smog tests, I contribute a lot of that to the HEI ignition considering it had the Holley 500 which is pretty fat on the 305. Good thing the truck now is exempt from the smog tests.:upyes:

[ilvracn]

i agree big block, the newest american hotrods are pulling 6 and 7 hundred hp, with cat converters. can't be restricted much.

[ilvracn]

i think fuel injection, and hei make all the diff. in cold start driveabilty, and cold engine wear. i think choke tends to wash cylinders, and wear rings, and cylinder bores. with the gas we have now and not being able to buy oem choke coils, just cant to get choke to work right. i find myself adjusting them all the time, with the change of seasons. i have several vehicles with carbs, and i prefer manual choke.

[bigblockv6]

Running a true exhaust on my 02 LS1 Trans Am with stock dual converters and there is virtually no restriction in the exhaust system and it more likely maxed out so I have to by a tuner for it. :thumbsup:

[FetchMeAPepsi]

I don't know about other people, but it wasn't ever the restriction that made me hate cats. It was the cost. Paying $800 bucks for a glorified muffler and being told that you couldn't drive legally without it was the killer for me. I'd just as soon drive no exhaust as have a cat to pay for every few years. Not everyone is a rich politician.

[bigblockv6]

Talk about costs, it's expensive here in California because when you have to replace a converter it has to have a specific California certified converter, so it will be dated and have a compliant number on it. As far as restriction it was the old pellet type of converters GM came out with in 1975 that were the worst:pullinghairout:

[FetchMeAPepsi]

Talk about costs, it's expensive here in California because when you have to replace a converter it has to have a specific California certified converter, so it will be dated and have a compliant number on it. As far as restriction it was the old pellet type of converters GM came out with in 1975 that were the worst:pullinghairout:


Yeah that california's crazy sauce. Always spending money and driving up costs but wondering why they're broke. I'd have to move next door to Utah or AZ or somesuch, though AZ/NM is getting just as bad on some things. The weather's beautiful, but the government... :banghead:

[bigblockv6]

I'm thinking about an eventual move to Nevada to get away from all the nonsense going on California:pullinghairout:

[FetchMeAPepsi]

I'm thinking about an eventual move to Nevada to get away from all the nonsense going on California:pullinghairout:

I wouldn't blame you a bit for that. CA used to be a great place from what I hear. Like 1960's and 70's. Maybe 80's? Since then it's gone a bit nutty.

Nevada's got alot of the same goodness though, without all the crazy overcontrolling laws. :thumbsup:

[ilvracn]

i agree, california regs are terrible, cat prices are rediculous. i'm in iowa, so i'm far enough away from cali, i don't have to deal with those cars much. some vehicles cats cost more than the car is worth.

[TJ's GMC]

CA is pretty much The worst state to live in. Just look at their political views(far as I go). And they think that stricter gun control is gonna help....Really?

The main issue I've have with cats is that it takes the sound away from the exhaust system. The new camaros supposedly have high flow cats in them.....still they are way to quiet. Heck, my 305 is louder than they are!

[bigblockv6]

It's because the new Camaro's run 4 converters along with quiet mufflers My 02 Trans Am has two converters and an aftermarket Bassani True Dual Exhaust with X pipe and it's plenty loud:ahhhh:

[TJ's GMC]

It's because the new Camaro's run 4 converters along with quiet mufflers My 02 Trans Am has two converters and an aftermarket Bassani True Dual Exhaust with X pipe and it's plenty loud:ahhhh:

Ah ok. 4 cats? Sheesh!

[br-549]

So let me give an update and attempt to but this post back on track. We have removed both fuel tanks from the bus and they are both on pretty bad shape. The main tank feel like there is prop 2-3 pounds of tar sludge sliding around. My original plan was to use a chemicals and then a steam jenny to clean the tanks via the sending unit holes but as my luck would have it there are 2 baffles/ 3 chambers to each tank. The plan now is to cut access ports to properly clean the tanks and then make steel plates to seal them back using gaskets and screws. The sending units are also toast- the are AC brand model C if anyone has some spares. So, in a nut shell, i do believe that the tar/varnish in the tanks is what caused the valves to stick. Thanks for your insight and assistance. JA

[tommr]

BR the valves sticking on the cold start is classic varnished up guides. When the engine is hot everything moves but when it cools down the guides get very tight. Fresh fuel on top of the tar sludge was probably sending "thickened" fuel to the engine. The 401 in our 47 Clipper sat for 24 years in a barn. Had tarred up lines but tanks were pretty much just rust. Eventually had the tanks blasted inside and out and coated inside and out. Google up gas tank repair or recoating and you will see outfits offering the service. Ours have been good since doing them in 2004. Sounds like we have the same baffled 42 gal tanks. We did Myrtle Beach, SC last week of June. Did the 625 mile return to Philadelphia in 1 day. Glad you made your OH trip.

[br-549]

Hey, Always great to hear from another FLX owner! Great looking bus! You don't see many any more with the original seats. Are you a member of the Flxible Owners International? If not you need to join us. We have a rally in Loudonville Oh every even year in July. email me at jerry.ashley28694@gmail.com for information.

We have the tanks out of the bus. I drilled 2 four inch holes in the top of one tank. It is terrible inside. I am looking into having new tanks made. They did not leak but these would never stand being sand blasted. there is about 2 inches of tar, rust and crud in the bottom and are paper thin. I don't know how it even ran. Thanks for the reply. Take Care, ja

[tommr]

Hi Jerry. if the tanks are thinned out you probably don't have much choice but to build new ones. There may be a universal style available that would physically fit the space but you might lose some capacity. Ive seen the OH event but its a conflict with Baseball stuff. Our bus was originally a Warner Bros Studio fleet unit that was driven East in the early 70s and parked in a barn. That's why the interior is intact. Stitched in new sides on the backrests and new foam last year. Did full exterior LED lighting this past winter/spring. New lighting harnesses as well. Original harnesses throughout were aluminum wire and had tons of issues. Eliminating old light wiring was a huge help. Inspecting and repairing engine and dash wiring as needed. It will get a better dash layout and complete rewire when it gets re engine. The fun doesn't end. Tom