170 drinks antifreeze

[Aluminum magnet]

Struggling here with the 3.7l. Last season we replaced the head gasket, points and set timing, cleaned carb and set, changed oil and filter , fuel filter, replaced cracked manifold and reservoir with new aluminum style, plugs and wires, soaked and flushed exchanger, New thermostat and cap, new impelller, outdrive serviced. She ran good but would always lose a little coolant (1/4 cup a day) and temp started to creep up. Always stayed below 200. I thought it may be from the reservoir mounted so low so I checked the line and it's fine. This year she runs good, but temp is higher so I took the infrared laser temp checker and at the #3 exhaust port I saw 350 deg. Coolant temp stayed around 200. So we head for home and compression checks. #1- 150, #2-150, #3-140, #4-160. See the pictures of the plugs, looks like #3 has something spraying on it. Any thoughts gentlemen? What would be the common failure mode for this scenario?

 

[Bt Doctur]

If your not burning coolant then suspect a leaking riser/manifold gasket or a leaking heat exchanger. Plugs look a bit hot, what number are they

 

[nola mike]

Reservoir gasket is always a problem, tend to leak into#3 and 4. Heat exchanger another culprit. Really need to pressure test the system though so you don't have to guess. You can borrow a tester from your FLAPS to see if you're holding pressure and then pinpoint the leak

 

[Aluminum magnet]

Didn't think of that. Thanks. System does stay pressurized well, and not a drop out of the cam weep hole. L to R the plugs are 1,2,3,4. Any easy way to tell if I'm burning coolant? Oil looks great and stays clean. Appreciate the help

 

[Bt Doctur]

and the firing order is 1342 but what number are the plugs ,they look to be a bit on the hot side.

 

[stonyloam]

Those white insulators might be an indication of antifreeze getting into those cylinders.

 

[nola mike]

If you're losing af, the system won't stay pressurized. You need to test with the system empty.

 

[Aluminum magnet]

Sorry it took a while to get back . Plugs are AC 43ts. I am really not familiar with pressure testing. I have the system drained. I can borrow a pressure test set up, but could someone walk me through what to look for and where? Sure do appreciate it.

 

[nola mike]

Pressurize to 15lbs or so, and see if it holds the pressure. Will drop relatively quickly if there's a leak. If so, well, that's when the fun begins. You'll have to listen for the air escaping, and figure out where it is.