2.7L and timing chain. - TTORA Forum
 
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post #1 of 14 (permalink) Old 04-03-2008, 07:26 PM Thread Starter
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2.7L and timing chain.

I have been doing some reading around and yes some searching about the 2.7L and timing chain. My truck has 130 000 miles on it and I am getting mixed answers on when I should look into the chain. Some say if its not making noise to leave it and some say replace.

I guess my biggest concern is what happens if it lets go? I read about the 3.4L and someone mentioned it was a non interference engine, now I am not certain what this means but what I concluded was if the chain/belt lets go you will just coast to a stop then it will have to be replaced/fixed. Is this the case with the 2.7L? If the chain lets go and is going to cause major issues I will look into getting it replaced but if all thats going to happen is Im stuck on the side of the road then I wont worry as much about it.

Few more things
2.7L = chain dont bother if its not showing any signs
3.4L = belt? recommended to change

I just always think of the worst and I would hate to see my motor crap out on me. Maybe I do to much reading and should just drive it and not worry?
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post #2 of 14 (permalink) Old 04-03-2008, 07:45 PM
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At 242000 i got a noise coming from my engine, I assumed it was the timing chain so i pulled the motor checked the chains{it has two one for the time chain and one for the balance shafts} neither were anywhere near the service wear limit, not even close. The noise turned out to be a crack in the exaust manifold on the underside where you cant see until it was removed. These chains are horrible to do because the fron diff has to be taken out, the oil pan removed and the head taken off. I thought it was easier to just pull the motor than go through all this plus i could replace all the gaskets and seals on the engine stand. Basically what im saying is your chain is good for at least another 100000 miles if you keep up on your oil changes. This is alot of work to do for just cause and would be a heafty bill at the dealership, about $1500. So just wait till you got over 200000 then worry about it because your gonna want to replace the head gasket about then as 2.7's are notorious for having heads crack around then this way you will already be half way there when you pull the head. At that time it would be good piece of mind but until then i wouldnt worry about it. The 2.7 is an interferance motor which means if it does break then it will cause serious engine damage. Chains are extremely tough and i have seen belts last alot longer than 120000 although i wouldnt recommend letting one go like that.

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post #3 of 14 (permalink) Old 04-03-2008, 07:52 PM
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chain

my dealer just quoted me 12-15 hours labor to replace the chains on my 2.7 WITHOUT parts. i have 145k took it to a shop CRACKED HEAD , cracked manifold. he took the head off and says the chain was good tight and the sliders where in good shape? i had no noise before the head cracked?
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post #4 of 14 (permalink) Old 04-04-2008, 03:51 AM Thread Starter
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wow this whole head racking issue doesnt sound very promising. How can that be avoided? Just replacing the head gasket?
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post #5 of 14 (permalink) Old 04-06-2008, 07:30 PM
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Originally Posted by snowmansimon View Post
wow this whole head racking issue doesnt sound very promising. How can that be avoided? Just replacing the head gasket?
No one really knows, or at least i have never heard. I do know this, most of the time when they do crack it is after 200000 miles and on the original gasket. I have never heard of one cracking if the gasket has been changed before an issue arises. My guess is that after so many miles[usually after 200+] The head castings develop typical wear and it makes them weaker then when a gasket does go it causes the truck to overheat which causes the head to crack, Thats my theory but no one has ever told me exactly "why" they do this. Just wait until you got about 190k on it then do your time chain and head gasket, & your truck should go for 300+. Just make sure to flush your cooling system regularly in the mean time because as antifreeze breaks down with age the chemicals become corrosive to gaskets which could cause premature failure of your head and or gasket. I use prestone dex cool in my truck as its rated for 100000 miles and its the same as the red toyota coolant only alot cheaper. I still flush mine every 50000.

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post #6 of 14 (permalink) Old 04-06-2008, 07:40 PM
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im just about to roll over 200k...All parts still orgianl except the manifold i just replaced.....I think i will drive it till it goes then if it does pull it out then might as well do clutch chains and everything.....are there some good deals on 2.7 longblocks thought i saw a post for longblock arond $1700? might be easier to just throw a new long block if you were planning on replacing head, chains, valves clutch etc...
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post #7 of 14 (permalink) Old 04-07-2008, 12:07 AM
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Originally Posted by knuckleduster271 View Post
No one really knows, or at least i have never heard. I do know this, most of the time when they do crack it is after 200000 miles and on the original gasket. I have never heard of one cracking if the gasket has been changed before an issue arises. My guess is that after so many miles[usually after 200+] The head castings develop typical wear and it makes them weaker then when a gasket does go it causes the truck to overheat which causes the head to crack, Thats my theory but no one has ever told me exactly "why" they do this. Just wait until you got about 190k on it then do your time chain and head gasket, & your truck should go for 300+. Just make sure to flush your cooling system regularly in the mean time because as antifreeze breaks down with age the chemicals become corrosive to gaskets which could cause premature failure of your head and or gasket. I use prestone dex cool in my truck as its rated for 100000 miles and its the same as the red toyota coolant only alot cheaper. I still flush mine every 50000.
How many 2.7 cracked heads have you seen???

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post #8 of 14 (permalink) Old 04-07-2008, 07:06 AM
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How many 2.7 cracked heads have you seen???
I have seen two, one in a friends truck and one in a 95.5 that was for sale but have heard of about 15 or so between this site and a friend who is a toyota master tech. Still seeing two of them with my own eyes is enough to tell me that its common. Even 22r/22re's do this with higher mileage,I had a 95 pick up with 186000 and started it up one day and it started puffing white smoke really bad so i took the head off and sure enough there was a hairline crack in between the water jacket and the exaust port on cyl #3

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post #9 of 14 (permalink) Old 04-07-2008, 11:12 AM
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Yeah i wouldn't worry about the timing chain or the head cracking. The timing chain can go for a long time and shouldn't be worried with unless you hearing noises or having problems or you are already tearing down the enigine. Also the head cracking or headgasket cracking is not a major issue on the 2.7 it has happened on several on here but its nothing to worry about. But it does seem to occur more on the 95.5 and 96 models.

98 Tacoma 4wd xcab Sr5 2.7 auto, 265/75/R16 Kelly Safari TSR's, Mossyrock's Sliders, 881's and billy's, OME dakar leafs and shocks.
83 4wd pickup 22r some sort of lift, 5.29's, 36 tsl's, lockrite and spool, and a complete disregard for body damage alot more mods in the works
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post #10 of 14 (permalink) Old 08-25-2009, 08:36 PM
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Thanks guy's, great post. FYI for those of us who are too lazy to wiki things...

A "interference" engine (like our 2.7) is a motor whose combustion chamber is designed in such a way so that the cylinder valves; at the extent of their travel ( full “lift”), would contact the piston if (at the same time) it is at the top of it's travel (TDC). E.G. If your motor is running and the chain breaks the valve train will stop moving, leaving the valves’ extended and out of phase with their cylinders’ piston. So when the piston reaches the top of the cylinder it will collide with the valves, and BANG!!!... Catastrophic engine failure.
So… if you should fail to correctly time the valve train with the crank rotation after a rebuild or as here; changing the timing chain. When the engine is spun you will (at best) flatten your valves and they will fail to seat. It is common (but not a rule) that engines that are designed as interference engine will have a timing chain for added durability and protection against breakage. Whereas; a non-interference engine will have a rubber timing belt that is less complicated and lighter (reducing drive losses).

For more info please consult your local librarian, they miss you.

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Last edited by Speedin'Ian; 08-25-2009 at 08:39 PM. Reason: lack of proofing
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post #11 of 14 (permalink) Old 08-25-2009, 10:11 PM
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For more info please consult your local librarian, they miss you.
Ok, so I called my mom... She does miss me, but she has no freaking clue what you are talking about with the timing chain. However, she can help with the wiki questions and recommends posting on threads that are already unanswered or < 1 year old. Oh, and they prefer to be called media technicians now. Thanks!

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post #12 of 14 (permalink) Old 08-25-2009, 10:45 PM
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post #13 of 14 (permalink) Old 08-26-2009, 08:22 AM
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For more info please consult your local librarian, they miss you.

I know your librarian misses me.
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post #14 of 14 (permalink) Old 12-29-2012, 04:43 PM
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I just completed my timing chain replacement this past week. My truck has 193k and I wanted to do a tare down mainly because I wanted see what my internals looked like and if I needed to plan on any major repairs. Timing chain replacement is a MAJOR undertaking. Like set aside a week.

It was a good thing I did it too, I bought my truck with 132k on it and the guy before me had a hack job air intake on it that had worn a hole in it. It looks like it had sucked in a bunch o' crap judging by the air intake.

I was glad I got all that trash cleaned out. The tensioners and guides were a little worn but not all the way to the metal (not bad for being open for the first time since it left Japan). Cylinder walls still had the cross hatching from the machining. Got the oil pan down and back up without dropping the front diff (PITA!). Would I do it again in another 100k? Probably not but I do feel better about going into the 200k+ range though.
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