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Overheated, losing coolant


chris78

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My bii overheated while I was flushing the radiator in preparation to replace the cooling system. I pulled over and let it cool down. turned out to be a busted hose. Was able to get it back with out letting it get hot again, ran fine, but blew a little white smoke. So I went ahead and put all the parts on, fired it up and drove it around, no white smoke, it disappeared.. The next day I noticed i'm losing a lot of coolant, and the engine seems muffled when accelerating, sometimes the power is low. I noticed a little foam under oil cap, the dip stick looks clean, but its gained a few quarts... I did a compression test after warming the engine and I got between 140 and 150 on all cylinders. I plan to pull the heads off. It also blew a lot of white smoke while warming the engine up.

Any ideas on where I could be losing the coolant and what to look for when I pull the heads? Is it possible its just the head gasket and valve seals? I've been around the engine and don't see anything leaking while its running. If it turns out to be a cracked head, I could throw another $500 in new heads for it, but wondering if its worth it.
 


RonD

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The oil level increase is troubling?

I would do the Glove test to see if you have a cylinder leaking pressure into cooling system
Easy and free

Remove rad cap, coolant level needs to be 2" to 3" below cap, lower is fine, so drain some coolant if its too high

Remove overflow hose and plug its port, use gum, putty, vacuum cap, .....??

Put latex glove over rad cap opening and seal it using rubber band or zap strap
Or you can use a balloon or even a condom in place of the glove

Unplug Coil wire, you want a No Start

Crank engine over and watch the Glove
If it bounces then you have a leak
If it doesn't move then you don't

100% accurate

If it does bounce you can remove 1 spark plug at a time and crank engine
When glove stops bouncing the last spark plug removed was from the leaking cylinder
 

chris78

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Glove doesn't move. Oil was a half quart over from the start, maybe i'm just exaggerating.. I did add an oil pressure gauge and swapped out oil pressure switch. Afterwards I topped off the oil so maybe i'm to blame. 140+ compression should be good no?
 

Nez'sRanger

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It sounds like a cracked head (or heads!). I bought my 89 ranger from a guy who said it was losing coolant. He supposedly put an effort into looking for leaks. (Really, I think he just changed the oil and put it up for sale) Anyway, I bought it and no more than two days later I found the leak... It was leaking into my oil! Ha! I tore it down took the heads down to a cylinder head shop, and they found a nice long crack on cylinder 6... About 700$ later (and quite a bit of fun, I must admit!) I got new heads on and she's running fine!

My advice to you. Change the heads. I highly recommend running a comment system cleaner through it, and then change the radiator, the hoses, heater core, heater core hoses, might as well throw a new thermostat at it while your at it! The stock heads are fine if it doesn't overheat. I even recommend having a shop change the AC condenser. The old ones are usually clogged with road debris. I eliminated my AC, but I understand many folks wouldn't like that very much :)
 

RonD

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Glove doesn't move. Oil was a half quart over from the start, maybe i'm just exaggerating.. I did add an oil pressure gauge and swapped out oil pressure switch. Afterwards I topped off the oil so maybe i'm to blame. 140+ compression should be good no?
Then heads and head gasket should be OK
Its a pretty simple test
140 is on the low side but if others were at the most 150 then its OK, within 10% average

Could be intake coolant crossover is leaking into air passage and/or valley but oil would get milky pretty fast

Coolant passages are at the corners of the lower intake
But drivers side rear and passenger side front are the pass thrus to heads
 

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When the head(s) on my '87 cracked the coolant went out through the exhaust and did not contaminate the oil (fortunately). If the truck's in decent shape I'd put a couple new aftermarket heads on it. And don't waste your time with pre-'89 heads.
 

chris78

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Actually I had already bought a new dual core rad, cap, heater core, hoses, belts, w.pump, thermostat, steering gear, fuelpump. After it overheated, I fixed the busted heater core hose and drove it around. Ran fine, just a little white smoke. Went ahead and swapped all my parts in. It stopped smoking. I live about an hour from where I was doing the work, so when I got home I checked the coolant and it was almost a gallon low, topped it off, and took it out again. It lost another couple quarts or less and started to blow white smoke again.

I'll take one more quick look around before I take the heads off and check them. I think like Ron says, its got good compression even if low, the engines got probably 250k+ on it, doesn't surprise me. I read in my manual where you can put a little oil through spark plug whole and re-run compression test. Says, if it raises compression, piston walls, or ring could be bad, if it does nothing then its probably a gasket or valve seat prob. I've seen aftermarket heads for less than $500, they're 86tm, but they have the large square rocker arm pads. There is another set i'm seeing for 89-92, ITM 60-5015, What is the difference? Any trick to spotting cracks in head with out taking them to a shop?
 
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RonD

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If you add oil to a cylinder the compression number will ALWAYS go up
How much it goes up can tell you if its rings or valves that are leaking the most

Rings and valves leak air, period, metal on metal seals can't hold air pressure very long. this is why slow cranking speeds show lower compression numbers, and why you should have all spark plugs removed before testing, so you have equal and faster crank speed.
The oil seals the rings better, but does nothing for the overhead valves, which is the point of the test

You need to add the oil to each cylinder as you test it, so do a DRY test, then add teaspoon of oil and do WET test, WRITE DOWN both numbers

I use a straw, dip it in a bottle of oil then put finger on the top, lift it out and put straw in spark plug hole then lift finger


The later model heads were less prone to cracking, 1989-1992
 
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Paulos

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It probably helps to have the throttle body wide open when compression testing also.
 

chris78

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My dry numbers are 1-140 2-148 3-140 4-150 5-145 6-148
wet numbers are 1-161 2-169 3-169 4-178 5-165 6-171
I didn't have a straw, but i had a med syringe, I just put about 6ml in each cylinder as I tested them one by one. I did it with plugs out and engine warmed up to op temp, wide open throttle. Cranked for 5 secs on each cylinder.

Might have been a fluke, but number 4 cylinder lost compression half way through the test but jumped up to 178, I re-did the test on 4, and it still read 178. white smoke almost disappeared for a few minutes. :)
 

RonD

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Never liked the warm tests, too hard to work with a hot engine, lol.

So dry you have a 145.25 average and no cylinder more than 5% away from that average

Wet has a 168.5 average, still under 10% variation

For averages on a V6 you don't use the highest or lowest cylinder, you add up the other 4 and then divide by 4 to get the average
10% of 145 is 14.5psi, yours are 5%, 7.25psi difference at most

So not seeing an issue

The 20psi jump wet is to be expected, about 15% above dry

If there is no jump up or very little that would indicate a valve leak
Probably only get a 10% jump on a lower mile engine
 

chris78

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It's hot but i've done this so many times now you get used to it, haha. Weird, i'm stumped.. hate to pull heads just to find nothing. Its definitely losing a lot of coolant. I just took it down the road 20 couple miles after topping it off. I lost 2 qts. I left it idling a bit and I noticed its not smoking. Earlier it looked like a locomotive. It runs ok, with an occasional loss of power. I checked all the hoses and the front of the engine and I don't see anything leaking or wet. Checked the floor inside around heater core and its dry, doesn't smell either. If compression is good and glove test passed I can't see there could be anything wrong internally. Got to be over looking something.

Drained the oil just to have a look, I don't know what antifreeze in oil looks like but here's a pic of it. Looks a little brown, muddy.


 

Paulos

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I would say that the crack(s) are located close to the valves in the intake or exhaust ports. Due to the look of the oil I would guess it's in an intake port, and most of the coolant is being combusted. Maybe the white "smoke" is actually steam. It can't be an issue with the short block (IMO), or you would definitely have a lot of coolant in the oil. Like I said, my '87 did the same thing back in '04. Not as dramatic as yours at first, but it was definitely the heads.
 

RonD

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Is it an automatic?

Have you checked if ATF level is HIGH?
i.e. trans cooler


2 Quarts of coolant in 20miles should be smoke show or overflowing oil in pan
And a heavy misfire if there was white smoke


You could get a cooling system pressure tester, basically a rad cap with hand pump and pressure gauge attached
Fill cooling system with water or coolant, wouldn't matter which
Leave oil out of engine, drain plug off
Remove all spark plugs
no start

Pump up cooling system to 20psi or so
Pressure should be dropping because there is a leak

Crank engine over and watch for a heavy mist from a spark plug hole, i.e. water/coolant leaking into that cylinder
There will be some mist from fuel, you could pull fuel pump relay and then drain pressure using schrader valve on engine
Check oil pan drain for coolant dribbling out
 
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Nez'sRanger

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Coolant in the oil looks like a mocha latte... Creamy, milky brown... From your pictures, it doesn't look like it.
At my work, one of the company trucks (a 94 T-100) was blowing coolant out the exhaust. It eventually died after overheating twice (guess the driver didn't notice the temp guage... Or the giant cloud of smoke billowing from the tailpipe!). It never had an oil problem, but water in the cylinders did it in.
I can't imagine it being anything but a cracked head... as extensive as such a tear down is, it seems to be needed. Best case scenario, a blown gasket... Not likely on a 2.9 though.
 

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