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Discussion Starter · #1 ·
This is in my ae92 and it's baffling me.

When I put the 7age in I put a new T-stat in.... worked fine, heater core worked and cab got hot. Motor lasted 50 miles....

Put in a JDM smallport 4age.... ran fine, same t-stat, worked fine, heater core worked and cab got hot. Pulled motor due to oil burning problems.

Enter new JDM smallport 4age..... had some rust on it and in the coolant passages. Used the water pump (known good) from the previous motor and prior to install used 120psi of compressed air through the cooling system to get rid of rust particles for several minutes. Same t-stat.... but all of the sudden the heater core isn't getting to temp and the lower rad hose felt cool to the touch.

Replace the t-stat. While doing so, I drain via the radiator to check for good flow, while cold it seemed to flow through just fine and drain quickly. Put the new t-stat in, put in about almost a full gallon of coolant/water mixture.... all seems fine. Drove it around town but the heater core never got warm.

One hose feels warm, return hose doesn't feel as warm. Lower rad hose feels much cooler to the touch. Rad is hot. Engine does not overheat one bit. Just drove 30 miles home from work and this is what I found out...... :headbang:
 

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Wonder if the heater water valve got clogged or messed up from the rust that you mentioned was in the small port 4age?
 

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Discussion Starter · #3 ·
I'm thinking that most likely is that the heater core is clogged..... but that would take a lot of bits and doesn't explain the lower rad hose issue.....

and when I did the t-stat the water actually didn't look too bad, still had a good green tint to it.
 

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Discussion Starter · #7 ·
meh... not too bad..... not too concerned... it's on the engine stand awaiting a new crank and 1 rod (have a friend who will supply me with them...)... plus I bought the first JDM motor (that smoked) as a rebuildable core, and just bought another car with a map bigport in it..... I have some spare motors at this time....

considering the 7a block and crank cost me $68... it's almost to be expected..... 11.0:1 compression and oversquare on a tired crank usually isn't the best idea.
 
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