65 Mustang 289 Swap Engine or Rebuild

dvelek

Member
Jun 5, 2019
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Alvin, Texas
Happy New Year. We have had overheating issues on this 289 and we replaced everything possible to try and solve the issue but after a compression check which showed us low levels we decided to rebuild the heads and do a valve job. Also replaced the intake and head gasket . After spending 2700 on the repairs the engine is still running hot and now has started to smoke which it’s never done in the 8 years I’ve had the car . We pulled the plugs and now we have oil showing up on the threads . I guess I’m at a point now to whether to pull it and this engine not knowing what shape the block is in with the ongoing overheating issues or bite the bullet and drop a crate engine in. Any suggestions would be appreciated as I’m afraid to put it on the road anymore at this point with all the issues I’m having . Thanks
 
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2Blue2

will be trying this sex one when I can find it
Mar 5, 2019
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we replaced everything possible to try and solve the issue

Be more specific...what parts?

Partially frozen distributer / wrong timing is a common culprit of overheating.
could be as simply as lower radiator hose collapsing and starving engine for coolant at speed.


Fresh valve job will pull oil past old rings
So new/rebuilt heads don't always work on old motor.
Being a 289 and 50 yrs old, the block will be scaling rust A LOT in cooling system and can plug a new radiator in short order.

I have an old 289 sitting around that I recently reinstalled not to long ago.
That rust turd is the magnet doughnut in this tefba filter. Filter was 75$ but worth it.
I have had to clean it every couple of days for the first couple of months, but easy to do.

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dvelek

Member
Jun 5, 2019
57
4
8
69
Alvin, Texas
After trying to figure out why the car was overheating we drained the coolant, high pressure flushed the block with water and with the block drain plugs removed using OTC’s cooling system power flush gun, filled the entire system with chemical rust removal for three days using two gallons of Evapo-Rust Remover with the old radiator and old water pump installed and circulated daily by running the car for about 20 minutes, high pressure flushed the system again with block plugs removed, installed a new high performance aluminum radiator, installed a new high flow water pump, installed a new 160F thermostat, installed new hoses with a stainless steel spring in the bottom hose, installed new hose clamps and added fresh 50/50 coolant. Then, we pressure checked the system and it held at 20psi. We also ran the engine while the pressure gauge was connected to the radiator (not under pressure) watching for bumps in pressure from a blown head gasket. After all that, the car still overheated. Timing was checked and we did record 30 degree initial. We dropped it to 18…it wanted the timing. Then, we check compression and #1 showed 129psi and #2 showed 40psi. At this point we stopped since we had a dead cylinder.
 

MustangIIMatt

I need something stupid to play with
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Mar 7, 2002
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Did you do a leakdown test to see where your compression issue was? Throwing fresh heads on a short block with bad rings is just going to make things worse.
 

dvelek

Member
Jun 5, 2019
57
4
8
69
Alvin, Texas
Just as a check before I spend the money and put this new engine on order has anyone ever had an exhaust system get clogged up and cause the car to overheat and smoke? I noticed a lot of oil inside the tail pipes and around one of the welds on the tailpipes.
 

2Blue2

will be trying this sex one when I can find it
Mar 5, 2019
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I noticed a lot of oil inside the tail pipes and around one of the welds on the tailpipes.

That sounds like bad exhaust valve seals or bad rings. (new heads old block right!?! )

I've seen a catalytic converter plug up and only let the car run poorly for 3 mins at a time.
I've also seen a car with a kinked/bent exhaust system run poorly with major crankcase pressure causing leaks and smoking out breather, lots.
 

dvelek

Member
Jun 5, 2019
57
4
8
69
Alvin, Texas
Well we finally did our engine swap hoping this would solve the problem. Everything new on the front side as well . Took her out for the 1st time today and temo shot up to 220 after 5 mins on the road . Not sure what’s going on. It’s got to be the radiator or fan causing the issue but it runs hotter down the road than idling which makes no sense . Any suggestions ?