Timing chain and oil pump wear?

I'm finally tearing into the head gaskets on my '05 4.0L.

I am not planning to replace timing components or the oil pump unless they show signs of wear. But having never done this before, I have no idea how much wear is normal. So, I'd appreciate if anyone can call out anything abnormal in these pictures.


The chain on the driver's side bank seems a bit looser than the one one the passenger side. The passenger-side chain and the main chain seem pretty well tensioned.


Also, the oil pump thing seems to be entirely loose in its housing. Not sure how this works. I will probably take it apart further to change the o-ring anyway.



Looks pretty clean to me for 180k miles?

 

That looks like a healthy engine; chain being loose on one side is normal; oil pump gear loose in housing is normal; you have nothing to really worry about. Inspect the timing guides; if they look good I wouldn't worry about them but not a bad idea to go ahead and replace them if they don't cost too much. Best do it now while its apart; I would replace the tensioner too while its out. On these engines you rarely hear of chain failure; everything seems to be well built.

 

The Toyota FSM is infuriating sometimes.


OK, TDC, check!




OK, chain tensioner removed, so now I'll make sure not to rotate the crankshaft any more! I sure hope I don't need to rotate the cams though...






God dammit! What am I supposed to do, put the chains back on and go back 40 degrees?

 

When you get a chance to explain how you determined the head gasket was shot, please do. I know about the bubbles, rough idle, smoke and missing. Was there anything else you could elaborate on?

I have an 05 with 125K and so far so good. I am concerned though.

 

Change the antifreeze when its required with the proper type. Most head gasket issues start with neglecting cooling system.

 

The first sign seems to be the "swoosh" of water from the dash area (heater core or hoses?) when you start the engine. I've had that since I got the truck (last year), and even before I bought it, I had accepted that it either needed or would soon need a HG. This had a certain appeal to me, since I've never done it before and I like figuring things out.

As a side note, the swoosh noise is almost always a sign that something is wrong with your coolant system. Not always the head gasket, but I've learned not to ignore this noise, because it always means that problems are taking root.

You can find differing opinions on this forum, but from what I've gathered, the '05 V6 engines have a design defect in the head gaskets, and they will fail in the mid 100k mile range even on well-maintained engines. The usual failure is cylinder-to-coolant, which is probably the least-bad kind of head gasket failure you can have, and it is a gradual failure that gives you time to detect it before doing damage to the engine.

What made me actually start this repair is that I started hearing the "swoosh" in traffic. That told me the rate of exhaust getting into the coolant was getting a lot worse, and I didn't want to risk overheating the engine, so I drove it home and parked it until I could do the repair. Before I shut it off, I let it idle and watched the coolant tank for a while. I was getting a small air bubble every couple of seconds or so. Never had misfires, rough starts, or steam from the tailpipe.

If you're worried, have your coolant tested for exhaust. Most shops can do this somehow. A minor leak won't show up on a compression test, so don't rely on that for diagnosis. Although it's a good test to do before deciding to replace the head gaskets.

 

Post a pic of the #1 chain (main) tensioner, located on the passenger side of the engine front. The extended length of the tensioner's piston will give an indication of how stretched the main chain is.

The side chain you posted looks fine. The #2 tensioners don't have ratchets unlike the #1 does, so a modest amount of slack even with new chains is unavoidable.

edit: that video of bank 2 chain does seem to show that the exhaust cam is a bit retarded on timing, assuming the intake cam is perfectly indexed on the timing marks.

 

I have replaced the coolant 3-4 times in the 125K miles I have owned the truck. I know that sounds nuts but maybe, just maybe, keeping the coolant like new may stop the head gasket failure. If not, it didn't cost a whole lot to do.

If it does fail, even though I have ripped apart motorcycle engines, I don't have what it takes to do the head gasket job on this one (as I sit here tonight). I may change my mind if the dirty ever does happen or try the product "Steel Seal" after draining the system of all the coolant because Steel Seal is not compatible with Toyota coolant and adding just water with the sealer. If it works, it gives me time to make up my mind as to a fix or a sell.

 

I'm not sure the root cause of these head gasket failures is known. Teflon-coated single layer head gaskets have failed me in other applications, and with much lower mileage than these seem to be experiencing before they let go. I know multi layer steel (MLS) gaskets are money in the bank in terms of reliability, and the revised gasket Toyota introduced (as well as Subaru on the 4 cylinder boxer, GM on the LS engine, etc.) all seem to reflect this confidence.

 

Here is the #1 tensioner before I removed it:





Here's a view of the exhaust cam timing. The engine was at TDC according to the crank pulley, before I removed it. But I can't be sure it didn't move a few degrees during removal.



I can't really tell, there's easily 10 degrees of parallax depending on the angle I look from!

 

Currently stuck on the camshaft sprocket bolts, which won't budge even with 30" cheater bars on the wrenches.

But the real reason I gave up last night was because I got scared away by a spider:









WARNING photo of spider below












I thought these things were made up to scare kids or something. But holy crap, they're real, and he might be in my garage now!

 

You can take both cams off together with chain attached, then work the bolt loose out of the car or take off with an impact wrench.
I think assembly would be a pain all together though best to take sprockets off to assemble

Good luck

 

Update:

• Cams are off!
• Heads are off and at a machine shop!
• Back is sore!
• The spider's name is Steven, I guess he was just out looking for a special lady friend.

I think I'll replace all the plastic chain guides, but keep the chains, sprockets, and the main tensioner. All of my guides look perfectly fine... but I've had those plastic liners fall apart and make all sorts of noise on other trucks I've owned around this mileage (cough cough *FORD*). And since this is the first (and hopefully last) time I'm disassembling an engine this far for a repair, I'm okay with being a bit proactive.





I'll do a full write-up someday. Hopefully. I'm at least taking pictures!

Thanks, and please keep up the supply of suggestions!

 

In hindsight this probably would have worked. I wound up breaking the bolts loose in place with an impact wrench and removing the cams one at a time.

Word of warning: As you saw from my confusion above, the Toyota FSM confused me into rotating the crank 40 degrees CCW from TDC before continuing the the cam/head removal process. I'm pretty sure this was a stupid idea, because as soon as I got the main chain loose enough to slip over one the sprockets, both banks violently freewheeled to a valves-closed configuration -- and nearly crushed my fingers in the process.

I've owned and used factory service manuals from Ford, Honda, Dodge, and GM... albeit each from different era of auto technology. But the Toyota FSM is hands-down the worst of the lot.