Well we already know one of the freeze plugs blew out.. and was "fixed"...

It probably overheated when this happened, and that's what messed up your heads. They put the rubber expansion plug in to fix the leak, but never fixed the head problem.

Makes sense to me.

 

Might have known about the issue...hard to prove that though, and in this state from a recourse point of view it doesn't matter on a used vehicle. Beyond this issue though, the rig is in cherry shape, and it runs great (that's what is so irritating!) <BG>. It was cheap enough. It just had $500 worth of tires put on, a complete trann flush and service, and a new 4x4 actuator motor (have all receipts). If I put four or five hundred into it in parts and spend some of a weekend or two and end up with a fairly cherry rig with a new top-end, it will still be a reasonable deal.

I'll know which jugs to scrutinize closely after putting the compression tester on this morning. I need to learn about the machine anyway, just like all my previous rigs, be they wheeled or winged.

Time to pull the tractor out of the shop and get the wrenches out...

 

MRGUY-
Yup, makes sense to me too. Seems like the only plausible explanation....although it's a "chicken before the egg" kinda deal. Did the plug blow out first and overheat/wreck the heads??? Hmmmmm....and why did the plug blow out???...because it was overheating? Do these rigs have faulty freeze plugs??? At least I can keep a sense of humor about it....for a little while longer anway.

 

Greetings all,

My kids brought home the red death, AKA kid flu, so I've been unable to hold a wrench let alone turn one for a few days. Finally felt up to building a fire in the shop woodstove today and checking compression on the Exploder.

So, these readings were taken cold and dry, with one exception:

#1: 134
#2: 142
#3: 152
#4: 114
#5: 140
#6: 148

Wasn't thrilled with the readings, particularly on the #4 (front driver's side)jug. Of course, I was expecting a couple of adjacent jugs to be low. Anyway, I squirted some marvel oil in the #4 and tried it again twice....came right up to 112-114 pounds again...no improvement.

So...I'm thinkin' that I probably have a small/slight crack in the head in or around the #4 combustion chamber. That would likely explain the rapidly increasing pressures in the cooling system to the point of failure, particularly when accelerating up a hill, etc. Am I barkin' up the wrong tree? Seems that there'd be a couple of low readings on adjacent cylinders if the head gasket was bad, correct? I'm thinking it has to be the gasket or a cracked head to do the pressure-thing to the cooling system, correct?

Just trying to identify places I need to give particular attention to examining during the disassembly process. Would appreciate any additional thoughts or inputs greatly....

Thanks again,
Rob

 

i still vote bad head gasket.

 

I second the Head gasket, leaking from the cylinder to the water jacket.

I would do a leak down on it before I pulled it apart, but that is just me, like to do a complete diagnosis before I disturb too much.

 

No you're not barking up the wrong tree, but exploratory surgery is the only option at this point. I would pull BOTH heads. Take them to a competent shop where they can be pressure tested, surfaces checked for straightness and a valve job done.

It might be worth the money to go ahead and buy the improved heads, but whatever you do, don't just do the right side. If it is a head gasket, the left side will most likely soon follow suit.

Also, while the heads are off, make SURE that you inspect the number four cylinder VERY closely. This is most likely a cracked head or blown head gasket, but do NOT miss the opportunity to inspect the cylinder closely while the piston is at the bottom.

Good luck,

 

Thanks fellas. Will do all as suggested and top off both sides. Figured if I'm in that far the top end might as well have an all-around freshening. Just a question of doing my heads of they're not cracked OR going with the beefier, "improved" heads for a hundred or hundred-and-fifty more smackers. If there is a real difference I'll just get the new style, as opposed to surfacing, grinding, seals, etc. on the old ones.

Aquanaut20.....are you in/around the lower mainland, or up in the interior? I've kinfolk in BC...spent quite a bit of time there....mostly up in the Dunster/McBride area southeast of Prince George. Have some cousins down near Kamloops too.

Thanks again,
Rob

 

why an i barking up the wrong tree?

i never said not to take both heads off and if they are off either replace them if in doubt or have them tested.

 

Upper Fraser Valley, where the mountains meet the sky, the rivers and lakes run cold and deep.

 

I want to post this here for the record so that it might help someone searching for answers.

The SOHC V6 in our shop vehicle, an Explorer, finally blew out what was leaking so we finally found the culprit. On the bottom rear of the thermostat housing a nipple blew off. We replaced the housing and all our leak problems have disappeared. It appears to be very safe to say that it was cracked and leaking when the engine warmed up. Pressure testing made it appear that the leak was from the timing cover and water pump, but apparantly that was a misdiagnosis.

Use a mirror if you have to and check the appendages from the thermostat housing which is a pretty large casting below the thermostat with several sensors and such.

Hope this helps someone.

 

Have you repeated the compression test and got improved results???

 

Thanks for all the input folks. Been busy and out of town too much to proceed. Time to start wrenching again....curious to see if it's a crack or the gasket.