The Stovebolt Site Forums The Shop Area Engine Shop Worst fears...realized?

Okay, I have been having trouble with my 305D V6 for a while now. I definately need a new carb, but I got some advice in another post (timing light question) and got some good advice (thanks jr) I had a feeling that maybe the valve timing was off by a few degrees, so i checked it (per jr's Instructions) and the timing seems to be all right. Now, I pulled all of the spark plugs, so I could turn the engine by hand with ease. I spun could spin it easily, until one area. I could not turn it after a certain point, and it sounds like something is rubbing up against something else in the engine. I can only describe it as wet rubber being rubbed. I have no idea what this means. Also, with the spark plugs in, I could turn the engine by hand, until about that same point, and I could hear air escaping, plus something "gurgling". I can only conclude that I have blown a head gasket, becuase I also looked at the plug in that cylinder, and it has rust forming, So I can assume that there is condensation in that cylinder. All the other plugs are fine, other than being carbon fouled. The engine could probably benifit from a valve job too. Oh, and heres one more thing. When I turn the engine by hand, I watched the distributor, and it takes about 1 inch of me turning the flywheel, to make the distributor start turning. Could there be some excess play in the drive gear for the distributor? My dad said this could still be the timing chain, but I wont be able to tell until I tear into the engine. If I do, I am just going to pull the engine, because the oil pan is bent in from the previous owner going over a rock that didnt "agree" with him.

Sorry for the long winded post, I just wanted to make all the details known.thanks in advance.

One of the problem areas we had with the GMC V6 line was distributor wear. Can't recall about timing chains, though. They will run forever if you keep your foot out of the carb and the rpm's down. Crank is not well-balanced and the rods will stretch. I would be pulling that engine and rebuiling it, rust in a cylinder is not good, and it does sound like the timing chain is stretched. Is it possible that your rubbing is coming from the oil pan dent interfering with the crank?

Jonathan - e-mail me if you need a decent running low mile 305.

Add two cylinders on the next engine, you will get better fuel mileage and the parts are cheaper
I am not saying that the V-6 wasn`t good, I am just saying it wasn`t good on fuel mileage

It could be as simple as a sticky valve. Fred do you own stock in rebuild parts or something? Your every advice is to spend thousands on a rebuild.

IMO, take off the head (in the truck) clean it up with a new gasket and maybe a valve job and see how it runs.

So far my original stovebolts have all been excellent runners. Eventhough I also have received the advice you better rebuild more than once. But, it wasn't necessary. I think both my current stovebolts will run another 50 years.

Also wondering if you took a compression check, just to see what that says. On the timing chain, even tho it's a double chain, I broke one once when I was just cranking the engine trying to start it.

I havent done a compression test yet, because I dont have a compression tester, but I am picking one up this week. I dont think it is the crank rubbing on the pan, the dent is at the back of the deepest part of the pan, and it makes it difficult to change the oil, because I really have to monkey with the plug. I think I am going to have to pull the engine anyway, just for that. I dont know if it caused any damage to the pickup for the oil pump, plus it needs to be fixed anyway. I might as well put a new rear crank seal in it while I have it out, it leaks a little bit. It seems strange that it started doing this suddenly. When we first moved here to Madras, it ran okay, but was loping a little bit at idle, and the vaccum was a little low. Then, one day I went out to start it up and put it in the garage, and it started up, but ran unbelievably rough. I cant describe the sound, but it was like a Chu chu chu chu and the whole truck shook. I pressed the gas pedal down some, but the engine didnt speed up or anything. I kept trying to start it, but it wouldnt do it.

This winter, the antifreeze that was in it froze. I dont know how bad, but none of the freeze plugs popped out. Could this cause a leaky head gasket?

By the way, when I go to pull the engine, where should the lift points be? Should there be three or four?

Before you plan on rebuilding that engine you may want to price compare. Your local GM dealer can get alot of Remanufactured engines cheap.You may spend 300+ at a machine shop then 300+ in parts and God only knows how much in tools you did not know you need. It can be very time consuming too. You may only be $500 away from a reman. engine that will have fewer headaches, plenty of fun to install, and a warranty Good Luck

Can you borrow/rent a cooling system pressure tester? that will let you know if there is a leak and where(if you look).

Gotta back up the reman idea if you don;t have the space and tools to do it. Otherwise the parts can be had through Kanter or NAPA to rebuild it. I recently threw a re-main kit from Napa in my 305E but had to get the new timing chain and gears from Kanter. Parts have run me about $500. That includes a carb rebuild kit, cap, rotor, coil, condensor, points, plugs, wires, and fluids and filters. A reman 305E motor was about $1600 from Advance Auto Parts.
My timing chain was stretched more than I wanted to keep. I didn;t realize how bad until I put the new one on. Be sure to replace it if you rebuild.
As far as swapping to a V8, base it on what you do with the truck and how original you want it.

Two cents' worth: about 20 years ago I spent $60-odd on a cooling system tester. The kid at the parts store thought I was crazy; I could rent one for $5 or so. I bought it anyway, found the problem on the vehicle in question.

And over the years have found several more on various cars and trucks. This thing has paid for itself many times over in finding cooling system problems before they left me stranded. *Especially* if you like older iron, it's well worth the money to buy one.

As to the rest of your motor troubles, I haven't a clue. 8-)
But good luck with them!

George
53 3600, running someday I hope....

I would rather just rebuild this engine. I want to keep the truck as origional as possible. including the origional truck color. I think, that it would be even more fun to rebuild this engine myself. I have rebuilt engines before, so this shouldnt be too bad. I already have the engine hoist and stand that I borrowed from my neighbor.(my new next door neighbor gave me permission to use them) so I have that portion covered. I have already pulled the transmission and am cleaning it up right now.

My feeling is, that just replacing the engine with a new one, would cheapen the restoration experience for me. Thats just my opinion.

You got my respect. I might do the same thing if I were in your shoes. It may take longer but when your done and you hear that engine for the first time, it's just ooooh! Not too many people are willing to go that far anymore.