Cleaning intake ports with head on?

What would cause the rings to fail?

 

The remanufactured head has a small amount of material removed from the head surface to straighten it out. This will raise compression in the cylinders covered by that head. If one head has a cracked valve due to overheating, the other head isn't far behind.

 

As far as the coolant passages go I would get the truck back together drop a bar of dishwashing detergent into the radiator fill it with water and let it run for a while. Repeat until water comes out clean

 

With the old cyl head and worn pistons you had some leakage of compression but wasn't noticeable . Now with the new cyl head the compression in those cylinders now will gradually cause the rings to fail

The cylinders wear over time and the rings don't seal as well anymore

 

Have you been able to hear the engine run? The reason I ask is this story sounds a lot like the plight of my old engine?

 

Yeah I was running the engine fine and driving it before taking it apart. The only reason I am taking it apart is to clear the misfire code in 3 so that I could pass smog to register it. I tried everything up until now to clear it until spotting the crack. I was doing a valve adjustment when I found that the passenger side was very out of spec (with #3 so tight that the intake valves had zero clearance). That was odd to me so I threw a camera down and found the crack.

The engine ran fine before. It would be a little shaky at idle, and if I cleared the misfire code, sometimes it would take a few days to come back. When I initially cleaned the injectors I'd actually thought I'd solved until it came back 3 days later haha.

What was the plight of your old engine?

 

I did a compression test before, so once I get it back together, I will run another one and let you know if the numbers change. Should be an interesting thing to observe and see if it really happens.

 

What eventually will happen is you'll start noticing oil leaks at gasket mating surfaces and at oil seals . This is due to over pressurization of the crank case from excessive blow by

 

By your own explanation though, wouldn't replacing both have caused the damage faster?

 

Yes !!!!!!

And to properly check the health of your engine is to do a cyl leak down test

 

So why would you suggest replacing both? hahah . And yes I did a leak down test prior to this as well. It was very insightful.

 

Since you have heard your run and I doubt heard any knocking noises, my old engine's plight is not relevant.

It was a case of the previous owner neglecting the engine's cooling system, it must have had a massive over heat that caused him to have the water pump, radiator, timing belt, and both heads replaced. After they did all that work, the engine developed a knock deep within the engine that was not from valve lash or bad rod bearings. It sounded like bad wrist pins. Also, I heard another 3.4L with the same noise. The engine ran fine, no missing or excessive oil consumption. It just had a deep knock. So the PO gave up and traded off the truck. I bought it and quickly went to work to replace the engine with an engine from a 70,000 mile 4Runner that had been hit in the rear. Since you are able to do your own work I think you will be ok. Just be careful not to invest too much in an old engine that may not survive the ordeal. Fortunately, due to my minimal investment, I was able to get away from the old engine and move to a much better solution in the end.

 

Thank you for sharing your story! Yeah, that has definitely been a concern of mine. The second I think I can't at least break even, I will get away from this thing. It's becoming a time thing for me too, and the time I am spending on it is at its limit. If it still has issues after I put the new head on, I think I am gonna sell. The chassis is not worth it to throw another engine in I don't think.

 

Last year we bought a Subaru Forester with a blown head gasket. We knew it was blown when we bought it. It was a clean looking car that would sell easily. So we put in all new belts, hoses, seals, gaskets, and head job. It didn't have too much rust but enough to make doing the suspension work it needed a real pain. After we started driving it, we could tell it was going to become a real money pit. So we decided to loose a few hundred and dump it quickly. Sometimes you've got to cut bait and get out without wading in too deep.

 

Knowing when to fold is definitely important! I hope everything goes well, but if it doesn't, I am gonna break even while I can for sure.

 

You could try evap-o-rust. Plug the bottom radiator hose and fill it up with the stuff.

I can't personally recommend it but I would do it if I found this. The sketch part is if you have another failed gasket somewhere the is plugged with rust, that plug will be cleared away. Could cause other issues.

Besides a chemical treatment, I don't think there is anything you can do to clean the inside of the coolant passageways.