Timing Chain Tensioner Replacement

[cpoh]

Car is coming up around the 100k km mark and have been doing a bit of research on this.

Is this a vital bit of maintenance? Ive been reading about the chains stretching naturally throughout the lifecycle of the engine and that the oem tenioner can handle this fine and even if the oem tensioner fails stock timing wont allow for chain slippage etc. Its a different story with aftermarket cams requiring upgraded tensioners and getting them changed more frequently as a result.

Does a damaged tensioner and stretched chain affect performance of the k20? As in will a new tensioner and as a result re-tightened chain recover/give extra bhp?

Its a similar story with valve clearances to be honest, most people i know havent bothered with either the tensioner or valve clearances with their k20's regardless of age. Would these be worthwhile doing in refreshing my engine?

Any advice appreciated guys 8)

 

[Kinli]

I've ordered a TODA heavy duty timing chain and a Hybrid racing tensioner, mostly for peace of mind I guess. I will be running IPS K2 cams, but still probably a bit overkill..

BTW, is there anybody here who has changed the timing chain without takeing the engine out? It should be possible..

Changing the OEM tensioner might be a good idea even if you don't run uprated cams. The tensioner itself doesn't cost much and the installation isn't that bad either. K20a.org has alot of info about the tensioners. hybrid racing also got a long article about the K-series tensioner.

 

[cpoh]

Cheers for the reply Kimli.

Im surprised more people are not interested in this issue, there's very little major maintenance to be done on the DC5 but if anything the chain tensioner is one of them along with valve clearances.

Have people noticed performance improvements when tightening valve clearances and installing a new tensioner?

 

[chiefpulsar]

its proberly due to the fact that honda engines are very reliable even the tensioner it's self so with that in mind no one really feels the need to replace it, but if you are concerened about it then change it for piece of mind

 

[C&S Evo7]

the timing chain and tensioner are designed to last the lifetime of the engine, the tensioner is relatively easy to change the chain is not so simple with the engine in,

if the chain is very worn thhen just changing the tensioner will not really help much , the distance between the teeth on the cam sprockets will change when the chain is worn so performance will deteriate as the cams are not in the perfect position to open and close.

at 100k km it should not require either its only 60k miles.

as for fitting any parts designed for racing they will require more maintenance and will have a shorter lifespan on a roadcar. a racecar engine is normally stripped for inspection at least once a year with prob less than 1000 miles, same goes for suspension etc. so bear that in mind when fitting any "Race" parts to your car.

 

[cpoh]

Cheers for the replies guys.

Ive been doing a bit of research and from what i can gather the timing chain stretches over time and the tensioner itself can be prone to failure thus not adjusting fully to the stretch. Worst case scenario on oem parts/tune is a bit of belt slap (small racket from front left of engine) but on cars with cas etc the strain can cause the chain to slip!

Can the DC5 timing be adjusted to optimum after the stretched chain has pushed it off a bit?

Also anyone heard of valve clearances adjusted having any effect on performance or is it just engine noise?

 

[C&S Evo7]

incorrectly adjusted valve clearences will of course affect engine performance,

i dont think the chain would ever slip, to make this happen everything else would have to be very very worn

 

Some wierd stories going on here guys..

Chains dont slip.

We have never heard of an NA engine needing a tensioner, they are on a rachet so they will not allow the chain to vary in length under power and retract under over run. We run std chains and tensioners on 300 bhp NA race engines.

If your running a 500bhp Turbo then i can't answer for that just yet, but maybe we will have information on that soon. If the product (super dooper after market tensioner) is from the states then its probably for Turbo use as them guys are crazy for going 250 yards quick...

Paul,
Buddyclub.
Proven power,
tried and tested advice. :wink:

 

[Dc5vic]

What sort of mileage are you lookin at before you need to start thinkin about takin a look at this?
Obviously it's a little more than the timing belt issue

 

[C&S Evo7]

probably never

 

[Dc5Dub07]

Found this info, might be worth considering changing the Tensioner, esp.if you are changing the cams:

Take Honda‘s K-series, for example. The crankshaft keeps the intake side of the chain tight but it‘s the tensioner‘s job to do so for the exhaust side. Without it, the cams would start spinning but ultimately just sit there doing nothing.
Honda‘s design incorporates both spring pressure and engine oil pressure. At low engine speeds, when oil pressure is low, the tensioner‘s internal spring moves its piston toward the timing chain guide, reducing chain slack. As engine speed and oil pressure rise, the spring relaxes and oil pressure pushes against the piston. But Honda‘s spring doesn‘t always work as you‘d expect, and excess tensioner piston travel and timing chain slack when oil pressure is low is common—especially during start-up when the spring is left to control the exhaust cam slamming shut all by itself.

All of this can lead to engine damage, even on unmodified engines.

Worst of all, you‘ll never know any of this is happening until it‘s too late. The problem is intensified once camshafts with aggressive closing ramps and/or stiffer valve springs are added. When the exhaust valves close while idling or during start-up, the tensioner‘s piston slams back toward its housing, which causes its teeth to bash against its ratcheting mechanism. This isn‘t a good thing since the ratchet and piston teeth are the only things that prevent the piston from being pushed in too far, which would otherwise lead to a dangerously loose timing chain that can potentially jump teeth, so keeping it intact becomes even more important. Once the piston‘s teeth wear down, the safety mechanism‘s gone. Meanwhile, as the tensioner‘s spring struggles to resist the exhaust camshaft‘s closing motion, the timing chain continues to slack, which is obvious by its kinking in the upper region near the camshaft gears. All of this is caused by a spring that‘s too weak to counteract the exhaust valves slamming shut and weak, undersized piston teeth that wear from repeated bashing against their ratcheting mechanism.

Until now, the solution was to “add a click” to the OEM tensioner, which reduces tensioner piston travel but doesn‘t solve the overall problem. Stiffer springs have also been experimented with, but neither solution addresses the bashing effect and potential for worn piston teeth.

 

[cpoh]

Exactly DC5Dub07, i read the same article (think it was on k20a.org?)

This seems to be a much discussed topic on most other k20 owners forums except here for some reason? There are stories in the US and elsewhere of guys losing engines due to chain slippage or tensioner failure, 99% of the time on tuned n/a cars with stage 2 cams etc.

Do any of the guys with big power on here have aftermarket tensioners or even replaced oem ones? I dont intend on going the cams route but was just looking at preventative maintenance more than anything.

 

[Dc5Dub07]

Do any of the guys with big power on here have aftermarket tensioners or even replaced oem ones? I dont intend on going the cams route but was just looking at preventative maintenance more than anything.

I spoke with the guy who tuned my Kpro and he said i should get the tensioner if im going the cam route, so id rather not take the chance and replace it anyways... Though he did say id be better off supercharging..

 

[C&S Evo7]

I have never heard of engine faliure due to tensioner problems in the UK on any k20 .
remember the k20s in the us are not the same as we have here. possibly the tensioners on the type r are different? maybe because of the increased rpm we have,

it sounds to me like it was written by someone who sells aftermarket tensioners.

personally i wouldnt bother or worry, have either of you spoken to a specialist? either Tdi North or TGM for their views?

 

[Dc5Dub07]

No your right C&SEvo, it was only recommended when having aftermarket cams installed..never heard of it causing engine failure either..

 

I suppose if a tensioner spring ever did snap it would cause chain problems at low revs but you cant even move the spring by hand it is that strong,so if it pops out on you it has to be reset in a vice.
Im with Si on this one, never heard of anyone in uk with a failure.

 

[macer]

When I got Toda Cams installed it was highly recommended to me that I change the chain tensioner to a Toda chain tensioner as the std one is not designed to work with after market cams

 

[Rob.]

Yep I'am having Toda cams fitted and advised to change tensioner as well, by Tdi.

 

[eg6-b18c6]

i have a UK k20a2 with IPS k2 cams, my timing chain tensioner failed on start-up one day but caused no damage.

i replaced it with an oem item, the toda seems to be just an oem one with a spacer fitted inside.this is in case the ratchet fails, the tensioner will not compress enough for the timing to jump a tooth. if you have access to a lathe, you can use your old tesioner to make a spacer for your new one and save yourself over £100.

I think there was another one in development by one of the US k20 swap companies which is a completely redesigned unit, the oem design is poor to be honest and is known to fail on other engines which use the same type. (toyota 1.8vvc and lots of motorbikes). a common solution on motorbike engines is to fabricate a manually adjustable one out of threaded rod, but this needs checking and adjusting etc.

The OEM tensioner is not a good design, and i think as these engines become older with higher milages we will see more failures.

Modified OEM seems to be the way to go for me at the moment, and if this fails i'll look into the other one (i forget the make but not the toda one) or make up a manual adjuster myself.

 

[Kinli]

I changed my chain & tensioner yesterday for the TODA heavy duty timing chain & Hybrid Racing Tensioner.

Quite a pain to do this while the engine is still on the car, but nevertheless, it is doable (just).

As you can see from the pictures, my chain was in good shape. Some stretching, but nothing to worry about. The tensioner was in good shape too (didn't take closer pics of it, sorry). The engine has done about 48.000miles.

This is Hondas tool to lock the camshafts at TDC. Very handy little thing!