Firebugs73

I have a 1996 tacoma 3.4 v6 4x4 king cab. 3 weeks ago it wouldnt turn over. Battery was good, pulled plugs to find cylinder 6 filled with antifreeze. Took apart, had head tested, it passed and good. All new gaskets and all back together. Both cams on mark, TDC, new belt, water pump, new oil, all fluids added. Goto start truck after rechecking everything. Truck starts and runs, no smoke or steam but it sounds like a diesel now and totally lost.
In 2013 it cracked both heads and did replace them then with all new gaskets, water pump and everything replaced from the block and up. It fired right up and ran great after that with no noises of any.
So even this time, it ran great the day before and had no noises. So my questions are what just happened to be making noises now? And it does fire up and run and sounds to be running good, just major noise and have been asked if I put a diesel in it lol.
Any help, ideas or what I missed for this to just happen would be great. I'm at the end of my rope and replaced all I could even think to have replaced. Thanks

Firebugs73

I think what has me so lost is, it ran great before and had no noises. After doing all this work again to have this unknown noise now that didn't exist before. I have seen many video clips from other areas and they have even said that Toyota says it's normal. Sorry, but theres nothing normal about that type of noise being make lol

75w90mantraN

Maybe a short video to help describe what you're hearing.
I might guess is it a knocking sound?

Firebugs73

I have tried to upload a video several times now and it isn't loading them up.I also just got done swapping the head with another thinking maybe valves but it sounds the same. Yes, it is knocking as if it jump timing, but if it did jump timing then it shouldn't run as it does.

flg8r22

iTrader: (1)

It doesnt sound like you changed the rings on the pistons? These are one of the first things that water/coolant begin to deteriorate and quickly. Bad rings will leave piston slop in the cylinders and give you a diesel sound. I have done several head gaskets and have had to re-ring all but a few times. I only have experience with 18r 20r 22r and 22re but im sure your v6 and any piston rings for that matter just dont hold up well to moisture

Firebugs73

No, I only did that 1 head gasket this time since it only had 20k miles since it cracked both the heads. I did feel the top of the pistions and none of them have any play or any wiggle in them. They all move smooth up and down and also didnt see any damage or marks inside the cylinders this time either. Sorry i still cant get any video to load up and have even tried to make a short one to make sure not to large to upload with no success either.

Firebugs73

Firebugs73

OK, with the help on my son, since kids seem smarter with computers. He got a link made with a video with the sound of my yota

75w90mantraN

Assuming you got no CEL and by 'everything' replaced that included the plugs and wires.

You could do a couple tests (compression test / vacuum test, stethoscope) if you don't want to tear it back down, but from a couple reads on the amazing net, others have ended up having to tear it down to see.

First link details nicely on vacuum test, really simple to use and can give you an idea if your rings are bad or getting there, and other useful info. Some details on the compression test.
https://www.yotatech.com/forums/f116...n-test-230800/

Second link assumes you have an engine knock. Case left off with pulling the heads suspecting possible piston rods/bearings issues. Very good read on all 3 pgs. While a visual inspection can suffice for some parts, others, you'd have to have certain tools to measure--
http://www.toyota-4runner.org/classi...ine-knock.html

If you're lucky, the noises are coming from the top of the head, either the rings, valves, guides; if not, then below the head-- rods/bearings, whatever components involved with the rotation of the crankshaft and pistons. The noise presenting itself awhile after a successful upper head job, if not from the re-install process (what you touched), could very well be from the parts you did not touch, that may have, as another member suggested, deteriorated from past damage. Your 96 is just begging you for more attention isn't it? If you didn't post the mileage, just out of curiosity what's yours at?

I'd do the vacuum test and try to get a stethoscope or long metal rod to pinpoint not only what cylinder is doing the noise but whether its more pronounced above the head or below the head. The compression test can also be a good diagnostic, though if you're not burning oil, then I might not suspect rings, but that's my guess. If you start having driving issues, then yes. The only for sure method is to tear it back down, sorry.

As I listen to it over and over and from comparing confirmed engine knocking noises, yours sounds different (not really a tapping noise).

Hopefully others can give you their advice from their experience. Best of luck!

Firebugs73

In 2013 when it first caused problems and cracked both heads, it had 320k miles. Now in 2017 when it hydrolocked cyl. 6 it has 370k miles on it. Main plan was replace left head gasket, head checked and passed. In 2013 compression test was about 100 avarage for both sides with lowest being about 80. I did compression test last week and it's much higher, 190, 190,185,185,185, 170. 170 being #4 also. Oil pressure is 36, so that I do know is pumping and working good. Also, every time i removed VC there was fresh oil in the cam area also. Gags for buckets meet specs of Toyota as well thinking them was worn out. So yesterday i did a head swap to try another head that is also good, with the same out come of it sounding like a diesel still. Toyota even tells me thats normal to just drive it, they must be idiots up there if thats what they think normal is gesh. Now today I have blown up the phone talking with alot of others that say they great with toyota's and it seem now i may have an answer. Due to the higher new compression, it has caused the lower bearings in the crack shaft to blow out and cause this noise. Even though there is no wiggle or any movement on any pistion when I try to check them from the top side. The only way to find out is to pull the entire motor out and try to replace them below, but i was warned by another Toyota guy who says he has 27 year exp. that that may not even work either. He says that they built them motors so tight that there isnt any play in anything and when yea try to rebuild it that it never works out. So i believe i maybe best looking for a 3.4L V6 motor to just swap out would be alot easier to do this time around. That wasnt the out cime i was looking for but it seems to be about my only chance to save it now from what i am learning. But if anyone else has more ideas, I am open to try again. lol. Hate to loose this lil old truck but I have put 300k mile on it in 14 years, I cant complain too much and shouldnt complain about it lasting this long for me even.

75w90mantraN

Aw man, sorry to hear. Everything has an end, but I bet even with either a rebuild or a swap, it will make it for several thousands more miles. Wow...almost 400k. Yeah, I heard stories of those who rebuilt theirs and went for awhile before the engine finally let down. It's one of those things now, whether you want to daily drive, occasionally drive, or sell. In the end it'll be your call.

Firebugs73

It does sound as if jumped timing, but it runs smooth. That just don't make since to me either. I just rechecked TDC on 1. Make on block is on mark also. Both cams on marks and put timing belt back on again. Got together and fired it up with same noise even. I did notice that crank casE makes 2 rounds to cams turn 1 round. Is it possible turn crank case is 1 round off to make it sound this way? I just tried that even and same result. Or should I try 1 tooth over maybe ? Lol. Idk. Just guessing now. Thanks

75w90mantraN

Nah, I don't think its a case of jumped timing. Also, putting the timing off by a tooth, prob add headache to your case. The crank : cam ratio is always 2:1 (if I remember correctly). If timing were off, you'd have a diff symptom, like a misfire or your cam/crank sensor would throw a CEL. Definitely wouldn't drive well.

On YT, there's a lot of really experienced folks posting on rebuilding older yotas so if there's nothing wrong with what you installed, then why not see if you can go further and examine the stuff below the head? Or take it to a shop. It will take additional time, but yeah, I think there's hope for you, whether you rebuild, swap, or have someone repair. But yeah, I agree, that noise isn't a normal sound, though it sounds cool.

75w90mantraN

Engine timing is also influenced with the throttle sensor, MAF, air/fuel sensor, injectors, and ignition components, which are all tied with the ECM, hence the CEL. But again, if those things are off, you would have apparent idling/acceleration problems and pending/actual codes. Without those problems, the problem points to underlying mechanical causes. Once the internal damage gets to a point, then it triggers things like crank/cam sensors in this case. By then there may be driving issues. At least that's my understanding.

I would definitely try to listen with either a stethoscope / long metal rod to see where the noise is coming from (one side/both sides, above/below cylinder head).

Hopefully other members here can advise.

Firebugs73

I have listened to it as best as I can. Main noise seems to be from the LT head still, even after swapping with another good head, but it's heard everywhere and loudest in LT head. Softer on Rt and even bottom. No CEL other the battery light and E break light showing up. (Got tired of putting AC, PS and Alt back on to keep taking them off lol). I did find a motor for $800. So with my 370k+ miles and this only having 140k miles I think it be a good swap myself plus it has been tested and said it runs good. Just got to find a motor picker to borrow since hate to buy for what I hope is a 1 time use and get a buddy to let me borrow his truck to go get motor. Then swap all my new stuff on the front of this motor so it's new when I put it all in while it's out and easier to do. Maybe after all that's running (I hope) then sit back and dig into this lower block to find out what or if anything let go down there. Maybe have a backup if needed ready to go then.

75w90mantraN

Sounds like a good deal. I spent roughly the same amount for an aftermarket cat a couple years ago.

Old parts, that what we usually do with them, trophy or for spares. I wonder what you find out when you investigate later on. One case I saw a video about with the 'diesel' noise was the result of a worn piston ring that made the piston put deep gouges on one cylinder. They also had lots of blue smoke coming from the back. Who knows...your case might be the early stages of what Flg8r22 had hinted at, and you decided to do something about it right after it started.

Still, nearly 400k on the frame, trans, and everywhere else, is pretty impressive.

Have fun and hope it all turns out well for you.

aowRS

I'm pushing for 400,000 miles on my original motor, transmission, rear end, u-joints, CV axles, etc. I bought the truck new and would immediately source a low-mile motor to swap in - when/if mine grenades.

Leaving in a few weeks on a 2,000-mile family vacation with the old truck...




Andreas

75w90mantraN

Well aren't you a lucky soul? 😊That's admirable quite honestly. But be safe on the road. That's another way we lose these marvelous engines, if not from wear and tear.