The truck is up on ramps right now as I pulled the starter to rebuild it and write up a DIY for the rebuild. For grins, I opened the radiator cap and performed the *SNIFF* test. I'm damn near positive I smell exhaust, which means head gasket. I'll get an independent nose to verify, and if that's the case then I'm going ***** to the wall to go ahead and replace it and save money on having a chemical test performed to check it.

 

Did you ever happen to use a wire wheel to remove old head gasket material? I've heard of that causing micro defects in the deck and head surfaces that can cause an issue like what you appear to have.

If you do tear it down that far, check the heads and deck for trueness, perhaps your previous machinist was a bit lazy on the details.

Sucks you haven't licked this thing yet

 

Nope. Tore it all down and then took it to the shop where it was tanked, checked for true, and then the bottom end built.

Or, it could be that when I originally installed the head gaskets, and screwed it up, that I didn't get everything as clean as I thought I did when I installed the new set.

 

When I pulled the heads last time, I rechecked the torque on the head bolts every ten minutes. An hour later, every head bolt finally checked good and would take any more torque. I figured it would take maybe 3 times for the bolts to be completely set, it took 6.

I also sawed the heads off some grade 5 bolts that matched the head bolt threads and used them as guide dowels when I lowered the heads on. Makes sure you don't move or fudge up the head gaskets.

Other things just to throw extra info out for the future readers. Standard headgaskets like felpro permatorque or stock headgaskets can only be compressed once, and you can't reuse them even if you haven't fired the engine over. You get one chance to make them seal right.

 

I have this same problem! New radiator water pump thermostat hoses motor only has 4000 miles on it still not solved?

 

It looks like I finally got this issue resolved as the culprit was the IAT. Read my thread asking if I had an Incorrect Sensor Arrangement and see where user drewactual advises on what could be the issue.

Drew definitely gets a Gold Star next to his name!

 

Congrats bud!!! Always happy to hear a solution. Now take that gold star down and quit being a teachers pet!!! jk

 

Thats a big freaking star. Wish I would get ones that big from my university.

 

and all the while I just got lucky..

If he had not mentioned the timing being erratic, and knowing that he had tried just about everything else, I never would have thunk of suggesting it..

I'll take that star sir, and stick it to my tool box- with the rest of the lucky crap I've accumulated over the years.

 

Well, an update. This past weekend, I loaded the truck and headed out to a local swap about 40 miles away. The added bonus is that it was HAWT (97º+). On the return trip the temp would get close to 200º and think about crossing and then would dip again. There weren't any wild fluctuations as I'd been dealing with previously, but they were still occurring. When I returned home I popped the hood, and sure enough the overflow was full; however, there were no signs it had been shooting coolant out the spout.

Yesterday, I stopped at the radiator shop where I'd been talking with the tech about this problem. He grabbed his kit, I popped the hood, and he depressurized the radiator a bit to shoot into the overflow and added some of the testing chemical to the testing tube and drew a sample from the over flow.

The verdict: I have a head gasket leak. The good news is that it's a very, very slight leak, because the testing chemical (very dark blue in color) very slightly changed color to yellow. I'm talking it went from dark blue to a blue/green and stayed there. As he tested, he'd release a bit more pressure from the radiator and then draw more coolant for the sample. It was still good that the testing chemical was not turning color very quickly. As he explained it to me, a bad head gasket leak will cause the chemical to turn bright yellow very quickly. Add to it that the temperature here has been 100º+ for the last week, and the truck hangs in at under 200º is a very good sign.

Overall, my conclusion is that the head gasket leak was being compounded by a faulty IAT, so Drew still gets partial credit for helping narrow down the issue. I drove the truck to work this morning (75º) and the needle pretty much stayed at 195º. Since I suspect there may be an issue with the plenum (I'm losing oil again) I can afford to hold off on any major work for a while.

Stay tuned this fall for a potential build thread.