2.9 cracked head??

stegomon · Apr 1, 2014

88 b2 2.9 with 4.0 rad

First time I did this.i pulled a large truck across the yard with deep snow.kept it revved at 3g RPM sometimes went to 3.5g RPM. Then I blew a heater core hose, changed to the heater hose and core.

Second time. Lots of deep snow in the yard. No plow truck. Had to use winch and tires to cut snow. Again engine revved at 3g. Truck boils but does not boil over?

3rd time. Ran for about 45min also used winch to pull atv out of a snow bank. It Got very warm. I want to say 85%.

So could this be a cracked head on it's way?

RonD · Apr 1, 2014

Cracked head doesn't care about use.

Cracked head or bad head gasket:
Compression in cylinder causes "air" to be forced into the cooling system, this displaces the coolant(it goes to overflow tank), the "air" doesn't cool as well as coolant, and water pump can't pump "air", engine starts to overheat.
You could be idling and engine would overheat.
Overheating can cause a cracked head.

What it reads like is that your water pump impeller blades might be marginal or fan clutch is, but it could be normal for your use.
At low speed with high load there is not alot of rad cooling vs engine heating.
Do you have the correct Fan Shroud on the rad?
This allows the fan and fan clutch to work better, the fan clutch is heated by the rad temp, in the winter it takes a higher temp to get fan fully engaged, if shroud is not there then cooler air comes in from the sides and fan never fully engages and fan is not pulling air thru all of the rad, just from the center, shroud is important.

I know many people who do alot of 4x4 "crawling", low speed/high load, switch to an electric rad fan, this provides better cooling at lower speeds.

Normal use of a vehicle is what it is designed for, so for a car/truck a higher load is always at a higher speed, even towing, so more air flow and rad cooling when it is needed.
While your use of the truck to pull things at low speed is common, it is not "normal" in the cooling parameters, like "crawling" is common but not "normal" use.

adsm08 · Apr 1, 2014

The other thing to remember about these cooling systems is that you can hear them boiling. Modern cars with degas bottles are sealed systems and should never boil. The 2.9's cooling system isn't actually sealed. The overflow bottle is open, and if the pressure in the system becomes more than the cap can hold coolant will push past the cap, out into the overflow, and boil, and you can hear it bubble.

Road Angels · Apr 1, 2014

how many trucks and cars do you think are out there that dont hold the required pressure to increase the boiling point on the older cars and trucks, about 35%

adsm08 · Apr 1, 2014

Road Angels said:
how many trucks and cars do you think are out there that dont hold the required pressure to increase the boiling point on the older cars and trucks, about 35%

Oh, I know. All manufacturers recommend replacing the pressure cap and the 3 or 6 year interval for coolant replacement. Most people don't bother.

stegomon · Apr 2, 2014

Should I try an efan and replace the raze cap befor I test to see if I have a cracked head? If I can test that?

stegomon · Apr 2, 2014

What size fan? Also would you use one big fan or two small ones?

adsm08 · Apr 2, 2014

stegomon said:
Should I try an efan and replace the raze cap befor I test to see if I have a cracked head? If I can test that?

Well a rad cap is easy and cheap. An e-fan may not be needed yet.

Two ways to test for a cracked head or bad gasket.

1) You can get a block test kit.

2) You can get a rubber glove.

The test kit is pricey, but comes with instructions.

The glove, you just put it over the rad filler while the engine is cold, start it, and hope it doesn't blow up like a balloon.

I would also pull the water pump off and inspect it. It may be marginal. If the find are eaten up weird things can happen.

RonD · Apr 2, 2014

Cold engine, remove rad cap, start engine
Let it idle for 5 minutes or so.
If head is cracked or head gasket is leaking, coolant will come out rad cap opening and then you will see a constant stream of bubbles coming from the rad cap opening.
Bubbles will also smell like exhaust gas.

Yes, one large fan.
Most try to find a Taurus fan at wrecking yard, you often should replace the motor on these since they will most likely be high milers.
Or you can get a new e-fan.

An adjustable temp fan relay that uses a probe inserted into the fins of the rad runs about $40-$60.
This turn the fan on and off based on rad temp.

Removing the belt driven fan will give you 3 to 5 extra horse power.

Stock Alternator will handle the load fine.

Fan power can run direct from battery(with in line fuse) but Relay should be powered by "Key on" circuit, so fan doesn't stay running with engine off.

stegomon · Apr 10, 2014

how about this one. bad vbelts. alternator pulley not enough tension. all wile using the winch. to low of an amp alternator? engine may rev to keep up?

2.9 cracked head??

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