motor problems again

[bigdaddyslotrat]

Well here i am again asking for help. (lol)
motor a 1932 diamond block freshly by somebody else. had a severe leak at the rear main (solved) was getting water in the oil (solved) but now after it runs for about 15 minutes is starts knocking a little and will stop running wait about 3 minutes and starts up and fine fine for another 10 minutes then . The whole time the oil pressure starts out at 60 lbs.cold. but the 15 minutes it's down to around 20lbs. then 8lbs. than the motor will sound real labored and stops.
any suggestions ???
was running 10/30 now straight 30 weight oil.
the guy that owns this thing is getting but me i'm like this is fun

just want to drive this beast!!!!!!!!!!!!!!!!!
thanks in advance

[BRENT in 10-uh-C]

Just curious, what color is the exhaust smoke? Could it be White in color?

I would start by checking the spark at the plugs the next time the engine stalls. This will tell you whether it is ignition related. If there is a good spark, then look for a fuel delivery problem.

[CWPASADENA]

You say after running for 15 minutes, is this at Idle?


If this is a fresh engine, allowing it to idle for long periods of time is not good for the engine. The engine does not oil well at idle speeds and something may starting to run dry.


Or,


What about water temperatures?


It sounds to me that something is starting to tighten up causing the engine to stop and then it will run again after it cools off a bit.


I think we need more information.


My opinion,


Chris W.

[mike657894]

check compressipon. check plugs for water wet or fuel wet after stall out. check head torque.

[bigdaddyslotrat]

thanks for all the answers
i to think it's tightening up and stalling so what rpm should we run at???? and the temp. of the water with a kitchen thermometer reads 150 almost 160

[30 Closed Cab PU]

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Originally Posted by bigdaddyslotrat

thanks for all the answers
i to think it's tightening up and stalling so what rpm should we run at???? and the temp. of the water with a kitchen thermometer reads 150 almost 160

If at 150 - 160 the motor should not be overheating.


Still could be an electrical issue. Condensers and coils often exhibit these symptoms when they are going bad. They run for a while and then cause poor running, missing, and car will not run. As previously posted, once failing quickly check your spark at a plug by spacing a spark plug lead about 1/4 inch from the plug and see what happens while running, once fails immediately crank the motor and see if there is spark.


If you have spark, loosen your gas cap, if it whooshes you have a plugged vent hole in the cap, try running it with the gas cap loose. With teh motor failing to run, immediately loosen the carb bowl drain plug or disconnect the gas line at the carb and see if you have a good supply of gas.

[30 Closed Cab PU]

Originally Posted by bigdaddyslotrat

thanks for all the answers
i to think it's tightening up and stalling so what rpm should we run at???? and the temp. of the water with a kitchen thermometer reads 150 almost 160

Not quite sure what you are asking about "what rpm should we run at?".


If asking about idle, an A with a good; adjusted carb, motor, and electrical system should idle down to 450 - 500 rpm. You will think the motor has died as you are stopping.

[katy]

after it runs for about 15 minutes is starts knocking a little and will stop running

At this point quickly put the hand crank in and see if the engine will turn over relatively easy, or seized.

[Hicktick]

Sounds like a piston swelling up too tight .

[bigdaddyslotrat]

thanks again guys
right after it stops running it's hard to turn over but wait just 2 minutes it's find and starts and runs fine till it does it again???

[Jim Brierley]

It has 60 psi oil pressure? A stock B engine will have 3-4 psi when cold and less than 1 when hot, at highway speeds. So unless the crank has been drilled for full pressure, there is more wrong than meets the eye. If the 3/8" hole at the front of the oil galley has been plugged, as it would be for a pressure system, this would restrict oil to the rods and be the cause of your troubles.

[bigdaddyslotrat]

thanks jim
i found my temp.gun so i was wondering what temp. might the block and head read when it's all warmed up maybe the back part is not getting the cooling it need ?????????

[George Miller]

Originally Posted by Hicktick

Sounds like a piston swelling up too tight .

plus 1

[johnneilson]

Whatever it is, continuing to run the motor is not going to heal it.

The pressure drop from 60 to 20 can just be a function of the motors speed, decreasing.

Time to pull the pan, look at cylinder walls perpendicular to the crank and look for scuffing or scraping. You will see it if a piston is seizing enough to stop the motor. Rotate the crank by hand to move pistons up to top position to expose wall.

If not a piston, look carefully at the rods and edges of rods. Discoloration is a temp indicator, if one is turning blue, that is your problem.

If not rod journals, look to mains.

When the rear seal was leaking, what was cause? Could the issue be a long bolt in flywheel rubbing on the rear main of block?

Pictures are required when explaining the problem, John

[George Miller]

If you have inserts you could be having trouble with the rear main not getting enough oil to the rear of the bearing.
The pistons are set to close by a lot of builders, you need .004 on number 3 and 4 . my guise is number 4 piston is to close and starting to seize up.

[katy]

Originally Posted by bigdaddyslotrat

thanks again guys
right after it stops running it's hard to turn over but wait just 2 minutes it's find and starts and runs fine till it does it again???

Sounds like a piston swelling up too tight.

Rings not having enough end gap can also cause this.

[Jim Brierley]

I've never measured block temps, I would think they'd be about the same as water temp? The block may be a bit cooler than head or water temp as heat is being put into the water by the head.

[Kurt in NJ]

I did some testing on my car, was curious after all the talk of warmer in the back,
at 160 coolant idling on warmup from cold ---

side of block water jacket @1-166, #2- 170 #3 -164 #4-167
side of block, cylinder below water jacket -- #1-192 #2-187 #3-186 #4-190

drove to fully warm, let idle for 40 min on 90 degree day ---all 195-200
after 20 min at 60 ---water jacket 182-184, below water jacket 225-227

[katy]

Originally Posted by Kurt in NJ

I did some testing on my car, was curious after all the talk of warmer in the back,
at 160 coolant idling on warmup from cold ---

side of block water jacket @1-166, #2- 170 #3 -164 #4-167
side of block, cylinder below water jacket -- #1-192 #2-187 #3-186 #4-190

drove to fully warm, let idle for 40 min on 90 degree day ---all 195-200
after 20 min at 60 ---water jacket 182-184, below water jacket 225-227

It stands to reason that the lower portion of the block is hotter that the top portion as there is no coolant jacket down there. That's why piston clearance spec is greater on these types of blocks than blocks w/full coolant jackets.