How Do You Properly Use a Straight Edge to Check a Block?

[m-mman]

The car is a 1942 Hudson 8.  The problem is overheating and combustion gasses in the block test fluid.

 

Remove head, resurface head, change gasket. Problem persists.

Remove head again look for cracks and imperfections. None seen.

 

Could the block be warped?  Buy straight edge. 

I put the edge on the block and place a feeler gauge under it. In a few places the 0.0015" feeler gauge can be pulled and pushed under the edge. But the 0.003" feeler gauge cannot or it is obviously dragging. 

 

The 0.0015" feeler gauge was pinched or could not be slid under the straight edge when checking the newly resurfaced head. 

 

Am I using the straight edge and feeler gauge correctly? 

 

 

Edited November 11, 2023 by m-mman (see edit history)

[Bloo]

Do exactly what you are doing, use a machinist's straightedge and a set of feeler gauges. Go diagonal as much as possible. Your'e gonna have a bad time with all those studs in there. Try a bunch of spots. Cover as much length as possible at a time. I don't know how much is too much slop on that, but .0015 is definitely OK.

 

 

[gungeey]

I was taught to place the feeler gauge down then place the straightedge over it. Trying to slide the gauge under results in little dings that will give faulty readings.

 

Is that straightedge painted?

 

[m-mman]

2 hours ago, gungeey said:

I was taught to place the feeler gauge down then place the straightedge over it. Trying to slide the gauge under results in little dings that will give faulty readings.

There are a lot of Youtube videos of people trying to shove the feeler gauge under the straight edge. At a few thousandths of an inch I knew that wouldn't work. (YouTube experts. . . . some good, many are dangerous)

 

2 hours ago, gungeey said:

Is that straightedge painted?

The bottom edge is bare steel. 

2 hours ago, Bloo said:

You're gonna have a bad time with all those studs in there.

The engine runs great, good compression. Running hot is the only issue. 

As expected the (steel) head was stuck and had to be removed with the persuasion of force. ONE stud came out during disassembly. The others are likely to require violence. To do that I can easily see down into the pit of engine removal and rebuilding. I hate to get into that. 

Edited November 11, 2023 by m-mman (see edit history)

[pont35cpe]

Overheating.. I suspect your flat-head engine may have a water distribution tube, have you checked for one, or what`s left of one? Located in the block behind the water pump.

[Ben Bruce aka First Born]

Running hot?   Or not cooling?   Different !

 

  Ben

[m-mman]

3 hours ago, pont35cpe said:

I suspect your flat-head engine may have a water distribution tube, have you checked for one, or what`s left of one?

No Hudson used an external water jacket.  Mine is not rusted and I ran Evaporust all summer.  The passages are very clean. 
 

These pictures are from several years ago when I started, but they show you the design. 

[m-mman]

3 hours ago, Ben Bruce aka First Born said:

Running hot?   Or not cooling?   Different !

Well put.  
It goes from dead cold to operating temperature (1/2 on gauge) in 3-4 minutes.  
It goes to 3/4 to 7/8 climbing a hill (power on) then drops to 1/4 coasting down. 
Opening the heater valve will readily lower the temperature. Hudson’s heater core is almost the size of a radiator. 

Full recore copper radiator. 
 

The car is driveable, but with it running so close to overheating I don’t have any reserve for really strenuous situations. 
 

Remember the block check fluid turns yellow slowly.  The symptoms all point to combustion getting into the cooling system. But I can’t see where.  

[EmTee]

6 minutes ago, m-mman said:

The symptoms all point to combustion getting into the cooling system. But I can’t see where.

Crack somewhere in the water jacket?  Did you try pressure testing the cooling system?  Did you run EG antifreeze?  If so, was there an issue with foaming?

[edinmass]

Flow check the radiator........not an "eyeball" it's OK......do an actual flow test. You need 35 gallons a minute.  Any less, recore it. Don't assume the recore was done right......been there, done that. The fact the heater lowers the temperature tells volumes. 

Edited November 11, 2023 by edinmass (see edit history)

[EmTee]

20 minutes ago, m-mman said:

Full recore copper radiator. 

Says the radiator was re-cored, but didn't specify whether an original style or 'high-efficency' core was used.  A core flow test would be a good thing, just to verify that it is open and wasn't compromised by any fine material that the Evaporust may have liberated.

[edinmass]

Lots of companies have been using heater core type replacements in the radiator , and they simply don’t flow enough. 

Edited November 11, 2023 by edinmass (see edit history)

[m-mman]

And the radiator construction doesn’t explain the block check fluid turning yellow….. ☹️

I’m beginning to to think that this is one of those Ed situations where it can be repaired but at how much time and money… ?

[edinmass]

Just saw the combustion gas comment……….

 

I would have other recommendations BEFORE a tear down…..too late now.

 

Sometimes you just need to tear them apart, and go through everything.

[m-mman]

1 hour ago, edinmass said:

Just saw the combustion gas comment……….

 

I would have other recommendations BEFORE a tear down…..too late now

The head comes off easily enough (now).  
As a point of diagnostic information while the block check changed, there was NO water in the oil.  
 

I ran the Evaporust all summer (cleaned things up well, but it wasn’t too bad to begin with) and pulled the head originally (first time) because a leak of Evaporust developed in an area between the block & head.  Really just a heavy seepage but it wasn’t coming out before months of rust abatement. 

[Bloo]

I suggest having the head magnafluxed. As for the block, I think you will have to just clean it really well and inspect with a bright light (and maybe dye). There are only so many places the combustion could be getting in. It has to be the head gasket or a crack/porosity in the combustion area somewhere.

 

Re-torque your new gasket a bunch of times after heat cycling.

 

 

[m-mman]

While there’s no evidence of burning, I’m thinking about relapping the valves.  It would give me some better views of that area. 
 

A subtle problem.  The most difficult to uncover.  

[Stude Light]

In any engine rebuilds or when diagnosing cooling issues I always, always, always just start with water only. I will usually add No Rosion to the water as a corrosion inhibitor and lubricant. 

 

I do this for a few reasons:

1) Water is cheap so if you lose some or have to dump it no problem (plus it isn’t hazardous to the environment)

 

2) If you do get a leak or overheat it isn’t going to mess up your paint. It is so much nicer to clean up.

 

3) Water is less viscous and has much better heat transfer properties than 50/50 EG so you pick up almost 20% improvement in cooling capacity.

 

Once I get everything sorted and tested for a while, then I’ll add in the EG if desired. My early cars just use water and No Rosion just because they cool better.

 

Doing this may also give you another data point if it greatly improves your cooling problem. I think you are getting good advice from a diagnostic perspective.

Edited November 11, 2023 by Stude Light (see edit history)

[Hans1]

 

My Hudson Essex cars all had raised metal around studs at top of block.

Counter sink holes in the head for studs. I use a 45 deg. 45 deg angle counter sink.

 

The likely hood of gasket pinching thus allowing clearance for exhaust gas or coolant to migrate.

Are you sure of the temp measuring device ?

 

Best wishes

 

 

[Stude Light]

1 hour ago, m-mman said:

While there’s no evidence of burning, I’m thinking about relapping the valves.  It would give me some better views of that area. 
 

A subtle problem.  The most difficult to uncover.  

This is a good idea. A crack in an exhaust valve seat would probably be noticeable after a good lap, thorough cleaning and using a magnifying glass. That would also explain the block check fluid.

 

You could also install your head without a gasket to verify the above theory by @Hans1

[maok]

8 hours ago, m-mman said:

Well put.  
It goes from dead cold to operating temperature (1/2 on gauge) in 3-4 minutes.  
It goes to 3/4 to 7/8 climbing a hill (power on) then drops to 1/4 coasting down. 
Opening the heater valve will readily lower the temperature. Hudson’s heater core is almost the size of a radiator. 

Full recore copper radiator. 
 

The car is driveable, but with it running so close to overheating I don’t have any reserve for really strenuous situations. 
 

Remember the block check fluid turns yellow slowly.  The symptoms all point to combustion getting into the cooling system. But I can’t see where.  

 

I would think that this is relatively normal variations. What speed are you slowing down to for the power climb up the hill? Obviously, air flow through the radiator is very important, slower you go up the hill, less airflow, hence temperature rise.

[Larry Schramm]

One other thing to think about radiator cooling is if the cooling fins are firmly attached to the cooling tubes.  I had a radiator that would not cool properly.  I had it boiled and flow tested three times and it would not cool.  ( I thought the radiator had a zipper for removal from the car at times ) It would not cool properly. 

 

I had the radiator recored and that fixed the cooling problem.  I believe that over time or maybe the radiator had water only and froze some that caused the cooling fins to loose some of the attachment to the cooling tubes so it did not get good heat transfer.

 

Just a thought and one of my experiences with radiators.