1989 Bronco II, 2.9L, 5 sp 4x4. Engine is consuming coolant. Replaced all hoses, thermostat, fan clutch. NO leaks on the ground. Exhaust is clean. Uses about 1 qt per day (40 miles driven) does not overheat if coolant level is topped off evey day. Runs a little warmer than normal if levl is low, but does not run hot. Runs and idles fine. Engine is a Crate engine replaced about 50K miles ago. It has upgraded heads made by a company called CIFIC out of California. I have not pulled all the plugs, but the ones I pulled looked fine. No indication of antifreeze in oil on the dipstick or filler cap. But when i pull it in my garage after driving it, there is an odor that seems like antifreeze coming from the vehicle.
I would say you you will need to remove all spark plugs and perform a compression test on each cylinder. This should help diagnose if you have a blown head gasket, cracked head or if you just have a leaking intake gasket. This is assumiong you have already performed a coolant system pressure test. http://freeautomechanic.com/blown-head-gasket.html
Already done the coolant system pressure test....planning on pulling the plugs this weekend.
I ran the compression test after warming the engine up...and all the cylinders were between 152 and 160...#3 was the lowest @ 152. #1, & #6 were at 155, #2,#4, & #5 were at 160. All the plugs were clean...but were gaped at about .050. They wer champian plugs so I replaced them with the stock motocraft plugs gapped at .044. I discovered some antifreeze on the #1 plug, but it was on the outside, and seemed to have dripped from above...possibly out from the valve cover. Will pull the valve cover off next, and see if I can find any leak. What is really strange, at least to me is on Monday I added about 1 galllon of antifeeze...1st time i have had to add coolant since July. Tuesday I added anothe quart, wed, I added another quart. Thursday and friday the level did not change. All week (mon-fri) I drove to work and back...about 35-40 miles round trip each day. The system was flushed and all hoses replaced about 3 1/2 months ago. I also replaced the thermostat and fan clutch at that time. At that time there was a pin hole in one of the heater hoses, that was causeing me to lose coolant. I ran it hot a couple of times back then, but never outside of the "normal range" on the guage. from July till this week I have had no issues with the cooling.
Don't forget the heater core that could be leaking. And it's hard to knotice if it is.
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