Head gasket would be my guess. Not to hard
SBC - How bad is this?
- Thread starter miker
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I really hope its the gasket,however as mentioned the 383 is highly modified, strocked and punched 60 over,you are most likely looking at a cracked block most 4 bolt mains are not high in nickel and are prone to cracking .A simple ser. no. check on the block can determine a high nickle content.
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- #23
Thanks for the ideas and thoughts.
A 383 is .030 over bored. Just about every 350 block can go .030 over without an issue. Other than the .030 over, what makes it a 383 is the 3.75 inch stroke crank. That's not really a lot of modifications which should make it prone to any sort of failure. Of course, this does not rule out a problem with the block but boring a 350 thirty thousands should not cause a problem. I built this engine for torque not horsepower so I'm not twisting it up or running high compression or a big cam. Its a very mild build, especially for a 383. Don't let the roller rockers fool you, they are just for show, not for go.
This engine has never overheated. Generally runs from 190 to 210 degrees but does get to 230 when pushing it up a long uphill grade or working through a big long rock pile on the trail. Even 230 should not be a problem and its never gotten hot enough to boil the coolant out.
I'm the only one who ever drives it or works on it so I know about the history and where all the fluids were added. So unless, I got a bad bottle of motor oil loaded with water...
A 383 is .030 over bored. Just about every 350 block can go .030 over without an issue. Other than the .030 over, what makes it a 383 is the 3.75 inch stroke crank. That's not really a lot of modifications which should make it prone to any sort of failure. Of course, this does not rule out a problem with the block but boring a 350 thirty thousands should not cause a problem. I built this engine for torque not horsepower so I'm not twisting it up or running high compression or a big cam. Its a very mild build, especially for a 383. Don't let the roller rockers fool you, they are just for show, not for go.
This engine has never overheated. Generally runs from 190 to 210 degrees but does get to 230 when pushing it up a long uphill grade or working through a big long rock pile on the trail. Even 230 should not be a problem and its never gotten hot enough to boil the coolant out.
I'm the only one who ever drives it or works on it so I know about the history and where all the fluids were added. So unless, I got a bad bottle of motor oil loaded with water...
- Thread starter
- #24
I'll be tearing into it over the next month. I just hope I find the problem and don't end up wondering what caused this.
Before I start to take it apart, as a suggestion from a friend and mechanic, I'll be dropping the oil pan and then pressurizing the cooling system and letting it sit that way for awhile to see if I can detect any leaks.
Before I start to take it apart, as a suggestion from a friend and mechanic, I'll be dropping the oil pan and then pressurizing the cooling system and letting it sit that way for awhile to see if I can detect any leaks.
You asked for our coments so naturally when someone says 383 it means race time . Only going from there,Good luck
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- #26
You are correct, I did ask for commetns and I appreciate all that I'm getting. I would think the same thing if it were not mine and if I didn't know the history of the engine. My only reason for building a 383 vs 350 or other flavor SBC was that the longer stroke produces more torque at lower rpm than the 350 and my cruiser is heavy.
More specs on the motor:
Block: "seasoned" casting no 3970010 (4-bolt version). Don't have serial no.
Crank: Scat cast 3.75" stroke, 350 mains
Rods: Reconditioned stock 350 rods
Pistons: KB cast pistons w/18cc dish (to reduce compression. Runs on regular gas)
Cam: Edelbrock performer (204/214 duration, .420/.440 lift. No lumpy idle. Good vacuum at idle.)
double roller timing chain
Heads: Edelbrock Performer RPM w/70cc combustion chambers
Rockers: 1.5 (stock) ratio roller tip
Edelbrock Performer intake and Q-jet carb
HEI distributor
Nothing race about it except maybe the heads but not very "race like" with the cam, pistons, intake, and q-jet.
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Do you use this since you have it on hand for your other rigs?
An FJ with a SBC and a Aluminum BeCool radiator does really need Toyota Anit-Freeze.
Looks like you caught something happening in time before anything major happened.
An FJ with a SBC and a Aluminum BeCool radiator does really need Toyota Anit-Freeze.
Looks like you caught something happening in time before anything major happened.
Just a note might be something ,In 2006 I did two 2001 Vortec v 6s that hade head gasket problems that leaked antifreeze into the base takeing out the bottom ends.Turns out it was the red antifreeze from the factory that was eating the head gaskets weather it was the combination of gasket material and coolant we dont know but GM went good for it. Might be something though.
- Thread starter
- #29
Do you use this since you have it on hand for your other rigs?
An FJ with a SBC and a Aluminum BeCool radiator does really need Toyota Anit-Freeze.
Looks like you caught something happening in time before anything major happened.
I was using it because of my experience with Toyota engines using Aluminum heads and Cast iron blocks and how well it has performed in regards to corrosion and buildup in the cooling system. I will likely find out soon how well it worked in the SBC.
I'm not telling you what to do as tech advice. This may even be bad advice since water can break the surface tension of the oil and cause the bearing to gaul.
What I would do is change oil, like you did, and then drive it so it comes to full operating temperature for awhile. Maybe slowly run out to Butte City and back. Then drain the oil and check it again when you get home.
If you pour the drained oil into a semi-clear bucket. In a few days you will seperate out and you will be able to see how much water is in there. It has to be coming from somewhere but you will know if it is 1 quart or 3 quarts,etc.
What I would do is change oil, like you did, and then drive it so it comes to full operating temperature for awhile. Maybe slowly run out to Butte City and back. Then drain the oil and check it again when you get home.
If you pour the drained oil into a semi-clear bucket. In a few days you will seperate out and you will be able to see how much water is in there. It has to be coming from somewhere but you will know if it is 1 quart or 3 quarts,etc.
- Thread starter
- #31
Hey Dan, I thought about doing something similar but I think I'm going to tear into it and just try to determine where the water is coming from. I'm convinced that it does have a problem somewhere and if I change the oil and run it I know I'll eventually see water in the oil again.
If I were on the trail or far from home and saw this I'd change oil and drive it to get home. At this point I'm in no big rush to fix it or take the cruiser anywhere. I'd rather not chance damaging any parts that aren't already damaged.
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- #32
I finally got the motor out and torn down. Water was definitely getting into cylinders. It looks to me like the source of the water was the head bolt threads. I used a sealant on them but it did not hold up over time (about 9 years). I either used the wrong stuff, what I used was bad, or I used it incorrectly.
I pulled all pistons and checked the rod bearings and crank journels and they looked good enough to just put in new bearings. I then pulled the mains and and they looked in similar condition and would probably be good with just new bearings as well.
However, the thrust bearing was nearly gone and the crank's thrust surface is all torn up. I didn't measure end play, it really was not necessary since it was so much but I'd guess somewhere around .100 or more. Yep, that's one hundred thousands and not ten thousands. I'm sure the crank is not worth fixing. It would likely be less money to just start with a new one. I noticed that the rod bearings were worn on one side more than the other so I'm sure thats from the excessive end play and crank walk.
I'm not sure what caused the thrust wear but I would have to believe that the water in the oil caused a lack of lubrication that acellerated the wear. I'm running an auto trans and know I checked the clearance between the torque converter and crank to make sure it was not putting pressure on it.
I don't think this engine had too many more miles to go before something bad was going to happen.
I pulled all pistons and checked the rod bearings and crank journels and they looked good enough to just put in new bearings. I then pulled the mains and and they looked in similar condition and would probably be good with just new bearings as well.
However, the thrust bearing was nearly gone and the crank's thrust surface is all torn up. I didn't measure end play, it really was not necessary since it was so much but I'd guess somewhere around .100 or more. Yep, that's one hundred thousands and not ten thousands. I'm sure the crank is not worth fixing. It would likely be less money to just start with a new one. I noticed that the rod bearings were worn on one side more than the other so I'm sure thats from the excessive end play and crank walk.
I'm not sure what caused the thrust wear but I would have to believe that the water in the oil caused a lack of lubrication that acellerated the wear. I'm running an auto trans and know I checked the clearance between the torque converter and crank to make sure it was not putting pressure on it.
I don't think this engine had too many more miles to go before something bad was going to happen.
Is it worn on the front of the engine or on the back of the engine or equal?
I'm thinking out loud here about the transmission pushing on the crankshaft. If it is a manual tranny, maybe the input shaft did not seat all the way. If it is an auto tranny, mabe the wrong flex plate or torque convertor?
I'm thinking out loud here about the transmission pushing on the crankshaft. If it is a manual tranny, maybe the input shaft did not seat all the way. If it is an auto tranny, mabe the wrong flex plate or torque convertor?
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- #34
Auto tranny. Th400. Its worn like the transmission was pushing the crank forward. Almost no wear on the other side. That side of the thrust bearing looks almost new.
The flex plate will be replaced. I may also replace the torque converter to be safe.
I'm pretty sure the parts were correct. Flexplate came from the machine shop. Torque converter came from the tranny shop. Maybe some incompatibility? Maybe a bad converter? Just guessing but would like to know root cause so it doesn't happen again
The flex plate will be replaced. I may also replace the torque converter to be safe.
I'm pretty sure the parts were correct. Flexplate came from the machine shop. Torque converter came from the tranny shop. Maybe some incompatibility? Maybe a bad converter? Just guessing but would like to know root cause so it doesn't happen again
