2007 random cylinder misfire

good luck, I just got told my motor is done from HG failure.

 

@Kiddnapped Tundra So I'm curious what your plan of resolution is. I'm hoping to be able to outline and make the process on my HG replacement more brief than the estimated 60 hours that I'm probably going to take on mine (first time this far into the 5.7 plus I'm taking my time), but that is no less than three weeks away. I'm sure each situation will be different but at 385K but no oil consumption and very clean inside the engine, I'm thinking replacing the gaskets is the better option than replacing the engine for me.
I'll know more once I get the heads off.

 

Steve, my friend is the head tech at his dealer. He said he saw pitting in 1 cylinder. He would hate to spend that much time tearing it apart to find out his camera was right. My truck has 216K miles and the engine they found has 93K.

 

I have a 2007 5.7 Tundra with 197K. I've been dealing with head gaskets for almost a year now. Blew one around last Christmas, it took the shop months to get it back to me. Blew the other one shortly after getting it back. Its now October, I just got the truck back and the engine is already misfiring. Is there a root cause to this that they're not seeing?

 

Did the heads get machined the first time? Did they use OEM gaskets?

 

Yes to the first question. I don't know on the second.

 

I would be curious to know if they are measuring the shoulder diameter on the head bolts to check for excessive bolt stretch. Also, did they change BOTH head gaskets the first time or just the one that was bad? I wouldn't even think of changing one without doing them both regardless. Not only is there a spec on the shoulder diameter, but also a "detorquing" sequence to avoid warping the heads as they are removed. Last, there is a torque proceedure that requires a certain amount of initial torque following sequence, then tightening 90° following sequence, then tightening another 90° following sequence. I've ordered a Snap On torque angle gauge (TA360) from Ebay for $70 that should show up Friday to aid the 90° tightening process.

I'll follow up later with the specs and the process I'm taking for HG replacement. I'm finally getting back on the project today after being out all last week for travel and coming back with a nice bug from the trip. I should finally have the heads off this evening and as long as they look good and I'm confident that the fail is the head gasket only, I'll head off to Toyota tomorrow to get all of the gaskets, seals and a few other parts I want to replace.

More to come...

 

Update: The heads are off and the gasket definitely reveals to be the failure. The black coating on the gaskets around the fire ring has deteriorated across the surface of the HG into the water cavity. Interestingly enough, this same thing was starting to occur in several other cylinders on both the bad gasket (RH) and the LH side as well, so I think the clock has been ticking for some time on HG failure. I was pretty amazed to see no visible signs of wear on the cylinder walls after 385K miles to the point that the cross hatching from honing is still there, no wear ring at the top of the cylinders either. Note that there are no signs of electrolysis or cavitation on any aluminum anywhere from the coolant.

I have the heads cleaned and just have the decks on the block to clean next. It was suggested by a co-worker that I use a Scotch Brite wheel on a right angle die grinder to clean those surfaces... I think that would be a HORRIBLY BAD IDEA. I'm using a nylon scraper, brake and/or carb cleaner on a rag to ensure I do not marr the aluminum and it will be squeaky clean.

Worth noting is that both heads came off with the exhaust manifolds intact, no problem. I don't think I'll even remove them now since there's no issue there and reinstall the heads with the heat shields in place to verify that they don't even need to be removed prior to removing the heads for future reference to others. Looking to take as much pain out of the process as possible.

I hope to wrap this up by the end of next week.

 

Just a short note to follow up on my head gasket ordeal. I did get the engine all back together and fired up late Monday night. Everything is going perfect except for an oil leak somewhere around the alternator, probably around the timing cover. I'll look into that in the next week but I'll go ahead and leave some of the most notable takeaways from my experience.

Bag or tag every component including ALL fasteners as you remove it with bolt counts. I had no bolts left over whatsoever, none missing.

Get two home storage containers for underbed storage for the cam plate components. No need to remove any of the cams or associated components, only remove the bearing cap bolts that go thru the plate into the heads. These are in sets of four, three into the heads and one into the cam plate which you will leave in place to keep the cams assembled to the plate.

I couldn't be certain on the factory timing marks for the timing chains so I made my own and highly recommend doing so. I made a single mark with a paint marker at the crank, two separate ones at the intake cam so there was no mistaking placement. Keep the chains and tensioners with the cam plates in the storage boxes and keep them clean so there's no need to solvent wash them. Turn the crank a few degrees past top dead center so you can rotate the cams without hitting the valves into the pistons. This is necessary to rotate the cams to orient the flat spot on the exhaust gear to allow removing the timing chain from the sprocket.

Don't bother trying to remove the exhaust manifolds on the truck, they can come off with the heat shields on the heads. I installed the heads with both the manifolds and new heat shields with new bolts installed (small $$ and very much worth it ).

I followed the shop manual and removed the steering intemediate shaft, but it is not needed unless you were to first remove the exhaust manifolds.

The Valve Grind Gasket Set from Toyota does not include the two O rings to seal the oil filter housing, so order them separately. It does come with the fuel injector seals.

I replaced every coolant hose, around 12 in all plus one hard line that had a good start of corrosion on the outside.

Alternator needs removed. Vane pump unmounted but tied back out of the way. AC compressor same. Tie up the entire wiring harness against the firewall, no need to completely remove it. Do disconnect it from the fuse box on DS and junction box on PS.

I highly recommend getting a Snap On torque angle gauge (TA360) for torquing the head bolts.

Last for now, don't even think about using a grinder or abrasive air tool to clean the deck and heads. I cleaned them with brake parts cleaner and carburetor cleaner followed up with a mild abrasive rubber stick to just remove the remaining "stain" on the aluminum surfaces. Use a shop vac to suck out the coolant an dirt from the block and other crevasses.

Give me a shout if anyone has questions I can help with, keep in mind I am not a master mechanic, just a mechanically minded person.

Steve

 

Wow, nice job. You just completed something many believe to be impossible.

 

Brief update 2-1/2 weeks later: Everything is doing fine but I want to note that the oil leak has stopped, and YES, the engine still has oil in it! I believe it was around where the head gasket meets the timing cover on the outside of the engine. I used ThreeBond 1184 for most of the sealing, exception to the top engine coolant cover where I used Toyota FIPG. I don't know if the ThreeBond has a tendency to swell and closed the leak or the Lucas Synthetic Engine Oil Stabilizer swelled and closed the sealant. At either rate, I'll take it! I swear by the Lucas that if you start using it, you are committed for life as you will most likely develop leaking if you stop using it. I've mentioned it elsewhere that I've used it faithfully with every oil change since 100K miles and left it out for one oil change after 200K and it developed a serious rear main seal leak. I drained off a quart of oil and added in the Lucas and that leak stopped within a week and never came back.

Give me a shout if I can help anyone on changing HG - with advice that is. I have NO DESIRE to do another one!!