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You could try some goo to seal the threads, but it sounds like you're just postponing the inevitable. With rust in the coolant system and a bottomed temperature sender, someone has already abused &/or neglected this thing. So even if you stop this leak, the resulting higher (correct) pressure will just blow something else out. So rather than waste this time, effort, & money just to spend more of each soon, I'd pull the manifold & install a better one. It probably won't be quick or fun, but it'll be quicker, less hassle, and cheaper than doing a bunch of wasted work first. A good way to see what you're in for is to get a junkyard replacement manifold. That'll also give you a good opportunity to collect some used bolts, since you'll probably need a few. Collect them from SEVERAL engines - not just the one you get the manifold from. Get at least one plenum bolt (to replace the T40 in the center), several of the short intake bolts, and a few of the medium ones (the one closest to the temp sender). I'd also grab some water pump & timing cover bolts for when you have to do that job.
These show 5.8s, but they're nearly identical to your 5.0L:
Postponing the inevitable is the goal here. In a few years this truck will be taking the GF on a 15-20k mile road trip to Alaska and back and before that trip I'll do through every single thing on the truck and hopefully get a crate engine to drop in. Until then, it just needs to be able to do the 8-10k miles a year I plan on driving it.
I applied the gasket maker about a hour ago. I won't be able to check it until Saturday evening as I will be out of town. Hopefully, I come back and it holds.
On another note, how much of a problem might these broken off threads be? In my mind they would've disintegrated as least partly in the intake and I shouldn't have to worry about them causing a major problem.
Here's a thought, since you're working with a low pressure application. Take the sensor out, stuff a greasy rag in the hole, find an adapter, probably called a bushing or reducer, that has internal threads like the sensor, and tap the hole for the outer threads of the bushing. The greasy rag is to keep the shavings out of the coolant passages. Basically, "helicoiling" an NPT thread. Should give you nice new proper threads for both parts. NPT taps are cheap and easy to find, and the adapters too. Any good hardware store should have them both.
I don't know the sizes you're working with but here's an example.
Any junkyard should have several decent used ones for a few bucks. Pass by a coin-op car wash on your way home to blast it clean, and then a machine shop to have it resurfaced.
Here's a thought, since you're working with a low pressure application. Take the sensor out, stuff a greasy rag in the hole, find an adapter, probably called a bushing or reducer, that has internal threads like the sensor, and tap the hole for the outer threads of the bushing. The greasy rag is to keep the shavings out of the coolant passages. Basically, "helicoiling" an NPT thread. Should give you nice new proper threads for both parts. NPT taps are cheap and easy to find, and the adapters too. Any good hardware store should have them both.
I don't know the sizes you're working with but here's an example.
At this point wouldn't it be better to pull the intake manifold off to tap it? That's a lot of shavings that are going to drop into the intake...
Originally Posted by BareBonesXL
stuff a greasy rag in the hole,...
The greasy rag is to keep the shavings out of the coolant passages.
Tapping a hole is pretty easy. Some slight amount of skill required to avoid shavings. They won't drop in to the intake they'll drop in to the coolant passage.
Plug the hole, tap it, take your shop vac to it, pull the rag out.
I noticed this time that the gasket maker and thread sealant I used last time seemed to have been pushed up and out of the threads when tightening down the sensor. No wonder it wasn't sealing.
I don't have a pitch gauge on hand so I can't know for certain if it's SAE or metric. My trusty HF caliper says just shy of 17mm which is ~21/32".
02-20-2019, 05:51 PM
