You are here:

Classic/Antique Car Repair/Model A engine overheat

Advertisement

Expert: - 9/26/2009


Question

Block w/gasket in stil
Jack,

I read your response to another guy who had engine overheat and can identify with that persons quandry.  I have a 1930 Murray Body Town Sedan that is now fully restored and ready for the road except for the engine heat issue.  Part of my restoration included a full engine rebuild including crank balancing, piston/rod balancing, resleeved to std. new SS valves, hardened seats and every thing else I could possibly throw at the thing to make it reliable.  I also installed a "Snyder" high compression head, a new premium radiator, new water pump and a plethora of other parts just to get off on the right note.  Unfortunately, in a thousand miles the engine blew a copper gasket between #3 and #4 cylinders.  From the looks of the gasket and head it was also leaking some combustion gasses out the driver side of the engine.   I was told to cut down the water pump impeller, which I did, and also to install a restrictor in the upper radiator hose which I also did.  I did both of these according to the recommended procedure and hole size on the restrictor.

The new radiator has not had nearly enough time on it to plug with sediment since the block was recently tanked prior to rebuilding it.  The engine runs strong (rebuilt carb and new distributor along with the HC head and B grind cam)but the overheat has me sweating (pun intended)over the engine head issue.  I've resurfaced the head and cleaned everthing up in preparation to reinstall it but this time I am using a B headgasket per Snyder's recommendation.  

Question:  In your opinion could the blown gasket and combustion leakage be attributed to my using an A gasket witht the Snyder HC head?

Has anyone ever considered mounting a B water pump but rerouting the hoses so the block is pressurized by the pump and the outlet from the head then goes straight to the radiator?

Thanks for listening and even more so for the knowledge you provide.


Regards,

David

PS, I have always run super premium fuel in this engine just on the off chance I failed to retard the spark on a hill so I don't think detonation was the issue here.

Answer
If there was junk in the water jacket, it would take just a few minutes to get collected in the new radiator that, I'm sure has the small madern tubes in it.  I did that and ended up using my new rad as a very costly filter for the junk that, I'm sure was in my water jacket.
OK, assume your jacket was clean:  I would lose the premium fuel.  It is in the wrong direction.  Go back to it when you get this thing figured out.
If the original head gasket was leaking gasses into the jacket, that would cause o/heating.  When it did o/heat, was it at low speed, under load?  If so, it is gases getting into the jacket.  If you had to go 45 mph for 10 min. on  a hot day, then it is heat rejection capacity.  If it was the low speed reason, then putting on a good gasket that does not leak will fix the prob.  If it was the high speed reason, then it is water flow, heat transfer, or air flow.  Cutting down on the impeller is a band aid.  The pump is too big, but that is only a problem if the rad is plugged.  I assume the impeller is tight on the pump shaft.
I have to go play golf, I will resume my wandering on this later today.

OK, back from golf.
If you drove the car 1000 miles, you must not have a temp gauge on it.  I don't think overheating caused the gasket to blow.  When it was o/heating, if you had foam in the top tank, that is a good indicator that something is blocking the water flow and causing flashing of steam in the jacket.  The restrictor trick is also a band aid.  All that does is cut the flow and hopefully increase the pressure in the jacket.  Take out the restrictor.  Make sure the timing is correct and the condenser is good.  If it runs good, all that should be OK.  
Now that you are sure the head is flat, make sure the block deck is flat around the cylinders.  Torque the head down, drive the car a bit and keep torquing the bolts until they hold their torque.  This could take a month.  
Bottom line; I think you had a leaking gasket.  Hope that was the cause.  Keep me posted on how you get it fixed.
Good luck
jack
ps, to answer you question:  I am not familiar with the snyder head, but I don't think that would be the cause, unless it did not give you a good seal around the cylinders.  Make sure everything lines up to pinch that gasket tightly around the cylinders.  If in doubt, try and old (flat) head.
jack
jack
    Questioner's Rating
    Rating(1-10)Knowledgeability = 9Clarity of Response = 9Politeness = 10
    CommentI should have (but did not) had a gauge on the engine-thermometer on the quail rad cap only. I now have a gauge for this next start up. The first indication of a blown gasket was a loss of power which I noticed at highway speed then it quickly developed into a miss. When I originally got the engine back from the builder, I flushed the water jackets with a high volume hose in both directions then used my pressure washer inserting it as far into the inlet and outlet as possible. There was a rusty red substance that came out and I discussed this with the builder who said it was most likely some residue left over from the pressure sealing process they do on old A blocks. The condensor is the new style along with the new style upper plate. Belt was tight and the impellor on the pump is also tight. All the usual checks were made but no glaring standout issue. Regarding the block surface. I determined the maximum deviation was .0035" and most sources indicate this is within tolerance for sealing. (I did have some heartburn as to why the builder did not deck the block.) Thanks again for your comments.


  • Add to this Answer
  • Ask a Question

jack bahm

Expertise

Only repair type questions on the 1928-1931 Ford Model A.

Experience

Owned one when I was 15 yrs old, and now have owned 5. Still own and play with 2 of them.

Organizations
Oakleaf region of MARC. Model A Restorers Club. I have put several Model A videos on the Oakleaf site that may be of help. Things like how to start the A, how to Time it, how to troubleshoot it.. Go to oakleafregion.org and you will find them. jack

Publications
"More than you need to know about cars." Just a small book for Car Nuts. Blurb.com "Model A Ford Tips and Hints" Blurb.com 2010 Many Model A movies that can be found on youtube.com/jackbahm

Education/Credentials
BSME LSU, 1958, Masters of automotive engineering from the Chrysler Institute of engineering, 1960, MBA Mich State, 1976. Worked as an engineer at Chrysler from 1958 to the end of 1991.

Awards and Honors
Two patents while working in auto industry.

©2012 About.com, a part of The New York Times Company. All rights reserved.