94 Rangers temp doesnt hold steady

RangerNielsen · Mar 12, 2014

I bought the truck 07/13, flushed out the Nasty cloudy green coolant out of it, put 50/50 in it. Blew the wheel bearings in 09/13, so truck sat on the back burner for a while. In early 02/14, I got the truck driving again and drove it for a weekend on a trip permit to do a few things before I sell it. I then decided against selling it, and did more maintenence on it. Then on Wednesday 3/05/14, I flushed out the old coolant, cloudy green again. I I then put some prestone coolant flush chemical in it ran it for maybe 45 minutes, let it cool down. I then drained the radiator, put straight water in (planned flush it to get all the chemical out), changed the oil with some 15w_40 diesel, new oil filter, new fan clutch and fan, new radiator cap, new air filter, new spark plugs wires cap and rotor. Started it up, let it warm up a little bit while I cleaned the crop out from in front of the truck, took it for a drive and ran it through second, and took it back home. Wasn't boiling over or anything when I got it home, so I parked it. I had my brother listen to it idle and we determined it was missing and my upper radiator hose was leaking at the radiator. I took that off, put it back on and tightened it down, and started the truck. There was A LOT of exhaust coming out and the radiator wasn't leaking so I turned off the truck after about 1 minute of idlimg. I checked one last thing in the engine bay before going in for the night, and the coolant was bubbling, not boiling. So I went to vent the cap to see what would happen, and it sprayed water out. I did the glove test and verified that it is a head gasket. The coolant valley under the thermostat is orange. It also has a new thernostat, forgot to mention that. I'm not sure if previous owners used head gasket sealer or not, but I do know the truck was gutless as he'll before the tune up, and still has issues with some hills before I knew I blew the head gasket.

RangerNielsen · Mar 12, 2014

Also, the coolant has always seemed to be disappearing. I'm not sure if it has been working it's way into the cooling valleys or if I've had a blown head gasket for a while. And the guy that was going to buy it doesn't want it now so I'm stuck rebuilding it. Oh well, more things for this truck to educate me on.

RangerNielsen · Apr 24, 2014

After doing some research, it sounds like the truck has had a blown head gasket since before I bought it, and it sounds like it was an over heating issue, which I am concerned about warpage now. I believe that one of the previous owners put head gasket repair in it to stop the cylinder leaking into the coolant, and with me flushing the cooling system multiple times, I washed out the head gasket sealer. The coolant valley under the thermostat is also orange, which leads me to think head gasket sealer was involved. The tune up may have played a role in the reblowing, too.

I'm also wondering, would running 92 octane in the tank aid in the blowing of the head gasket?

RonD · Apr 24, 2014

Did you do the glove test?

Cold engine
Disable coil, you want a no start
Remove rad cap and overflow hose
Block overflow opening, vacuum cap works
Put latex glove over rad cap opening seal it with rubber band, balloon or condom works as well

Crank engine, glove will start to bounce if there is a cylinder leak

Remove 1 spark plug at a time and crank engine
When glove stops bouncing the last plug removed was the leaking cylinder, put plug back in to confirm.

The reason an engine over heats because of a head gasket leak is not because coolant gets into the cylinder, it is because cylinder pressure/air gets into the cooling system, the pressure pushes out coolant into overflow and the air forms pockets that delay cooling in those areas so you get the up and down temp needle as the air pockets are purged then reform with new "air" coming in, eventually there is not enough coolant left and engine really gets hot.

No on the higher octane, low octane gas that causes "pinging/knocking" can eat away at head gasket seal though.
Octane is a minimum heat rating, i.e. 89 octane will self-ignite at a lower temperature than 92 octane.
89 and 92 octane have the same "power" per gallon, so one does not create a bigger "explosion" when ignited.
High compression engines need to run higher octane because higher compression = higher heat during compression, so lower octane fuel will self-ignite("ping/knock") if used.
An engine with under 9.5:1 compression can run on 87 octane without "ping/knock", running higher octane doesn't hurt or help performance or MPG, however fuel that costs more often has injector cleaner additives included in the price, but it is cheaper to run 87 and add Seafoam one a year($8), lol.

RangerNielsen · Apr 24, 2014

Yes I did the glove test and it bounced around.

I am thinking a previous owner blew the head gasket and then put sealer in it... they probably didn't know much about cars and that's why it over heated for them and I have prevented the over heating. Since the fan shroud, the temp didn't fluctuate much except going up hills, but even still didn't get passed the m, but it would boil over with out getting passed the m. I haven't been able to test the new fan clutch due to the blown head gasket and the truck not being driveable due to the head gasket being blown between cylinder and coolant.

The straight water I had in the truck ended up turning black, and the water in the over fill as well... I haven't run the truck much since I did the tune up and discovered the blown head gasket.

I have always had a huge air pocket in the upper rad hose that I was never able to get out. I tried the no spill funnel and that proved to not be effective. When the tstat opened, it would push coolant out and then suck it out of the funnel quicker than I could pour it in, so I gave up on that.

RonD · Apr 25, 2014

The air in the upper rad hose would be purged to overflow tank when engine heated up, assuming no head gasket leak is adding more air, lol.

You want to get the air out of the heads and heater hoses, as these can cause an air lock because it is trapped.

Air in the upper rad or upper rad hose won't bother anything, as engine warms up the coolant expands in volume, this creates pressure in the cooling system, when pressure gets to rad cap's rating, say 16psi, the rad cap's BIG valve is forced open, since any air in the system would be at the top of the rad it is the first to be vented to overflow tank where it bubbles to the top, next out would be some warmed up coolant then when pressure is below 16psi big valve closes.
After engine is shut off the coolant cools and shrinks in volume, that's when the rad cap's SMALL valve opens and coolant is sucked back in from overflow tank, coolant only because air has bubbled out of overflow tank.
Now all the air is out of the rad and engine, assuming no leaks

RangerNielsen · Apr 25, 2014

That makes it sound like there has always been a leak... i would fill the over fill to the cold line, and when the truck wasn't worked, it would suck all of the coolant out of the overfill, but whenever I checked, the rad would only be half full, even if I filled it completely and the over fill. Grr. ..

94 Rangers temp doesnt hold steady

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