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Old 08-12-2013, 03:46 PM
HotDakota HotDakota is offline
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Location: Golden CO
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Vehicle: 2002 Dodga Dakota Quad Sport
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Engine: 2002-2007 287ci (4.7L) PowerTech V8 235hp 295lb/ft
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Default What happened after I redid the head gaskets on my 4.7 part 1

So, after following jaymillers excellent dialogue on how to do head gaskets on a 4.7, here is what I did and found out:

To make my life easier, I went ahead and disassembled the air conditioning system - easy to do, put baggies over all the pipe ends to keep any crud out, and removed the radiator, upper cross member and a/c condenser just to make it MUCH easier to get to everything. Actually, the toughest part of this step was disconnecting the lower trans cooler connection....

I pulled the heads and took them complete with cams and followers down to Dettmers Automotive in Englewood, CO - excellent shop, Carl is a top-notch machinist, Dettmers came highly recommended, so if you're in the Denver area and need machine shop services, I would highly recommend them as well.

Carl pulled the cams and valves, pressure checked the heads for cracks and found none. Machined the head surface 5 thousandths to get them flat again and reassembled with new valve seals that were included in my Fel-Pro head gasket set.

While taking the heads off the engine, I was surprised at the lack of torque it took to break the head bolts loose, which made me suspect that perhaps when the heads had been redone previously, they had not been torqued to the proper spec. The head gasket was fine, but really trashed looking (it was a fel-pro), heads were fine and now the surface was flat. What Carl and I think was that this engine had been gone through previously (time unknown) and the head gasket and head bolts were both re-used, both big no - no's.

So, new gaskets, new Fel-Pro head bolts, and I went ahead and put in a new timing set as well - chains, guides and tensioners only, no gears as they all looked fine. Took my time to make sure I had all the marks and dots lined up, torqued everything carefully and buttoned it up. I did not use an angle gauge for the final 90-degree torque requirement for the head bolts, but drew a line across each of the head bolts from top to bottom so that I could see when they had 90 degrees of twist on them - worked fine.

Put the engine all back together after spinning the engine by hand many times to make sure I had no valve/piston issues, hooked everything back up the way it was supposed to be, installed a new water pump, thermostat, lower hose and cap, as well as a new fan clutch (it was shot) and a new electric fan (it was *really* shot).

Moment of truth - fired that puppy up, it started and idled beautifully, no unusual noises other than an exhaust leak at the joint, easily fixed with the help of my son, and voila! - I had successfully redone the top end of an SOHC 4.7 Dodge!! Woo Hoo!

But, did it fix the problem? Prior to tearing the engine down, I had the local Dodge dealership do a block check, and it did come back positive for combustion gasses in the coolant, so I absolutely knew then that I had a problem - there was always just that lingering doubt....

The day before disassembly, we took the truck for a nice easy cruise up Clear Creek Canyon, a fairly gentle climb through the Front Range of the Rockies, no big deal - and it overheated after about 8 miles when the grade started getting a little steeper.

After getting it put together, gave it a quick shakedown cruise over to Orielllys auto parts to return the harmonic balancer installer I had rented - didn't work, by the way, the adapters wouldn't fit the snout of the 4.7... - everything was tight, no coolant leaks, no oil leaks, no untoward sounds, so we jumped on I-70 and blasted off into the heart of the Rockies at 75 mph with the air going full blast (took two cans of r-134 to recharge the system, blows nice and cold) and didn't even come close to overheating - never got above the upper (or right - hand) white mark on the temp gauge, so if you have a 4.7 that seems to heat up only when under load but otherwise seems to be able to cruise around town without overheating, it is something with your heads - the gasket, head torque, warp, cracks, something. This fixed it.

BTW, Carl at Dettmer says he sees very few cracked heads, mostly just an uneven surface which allows pressure into the cooling system - my symptoms were overheating under load and blowing coolant out of the overflow tank, even when it was showing normal coolant temps. Whenever I took the cap off, the level would be low and I could add a quart to half gallon of coolant every time.

So, if you see a few drops of coolant on the tops of stuff in the engine bay or on the underside of the hood, start looking for other indicators, the most definitive one being a block test - I got my Dodge dealer to do it for $20 because the service writer didn't think I had a head problem - said he hardly ever saw 4.7's come in with an overheat problem and was convinced it was some other issue. Another service writer sitting in the office next to my guy later told me he see's 4.7's all the time, and knows there is a problem with warp/crack/gaskets, so just depends on who answers the phone.

Part 2 next.
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