85 250sx tapping noise

[rooster67]

Hello all!

I am new to the board here. I recently purchase an 85 250sx and love it. Gave her a nice once over with all of the usual things you'd upkeep. I have put a few hours on it and just recently i noticed a tapping noise coming from the top end. Let me first say that i have adjusted the valves to specs which was the first place i went. I verified that the top-end is getting oil, and replaced the oil filter as well. i (think) it is either the chain or the tensioner. When you first crank it cold the tapping noise is evident and exists steady from idle to open throttle. After about 5 minutes or so, once the engine warms up you can literally hear the tapping going away. It will stop tapping for a few seconds, then start again. Then the spurts of tapping become less and less and then stops completely once the engine is at running temp and at that point you would never know there was an issue. All the way through the RPM's its fine. I'm thinking that either the chain or the tensioner or BOTH are finally warming up and expanding enough to stop the tapping? I am a lurker here for the most part and believe you all know your stuff so throw me a bone please!

Garrett

[dougspcs]

Well tensioner is easy, two bolts..there is an inspection process I believe in the manual..

If that doesn't solve then next is chain, a tougher fix and unfortunately the more likely!!

New chain and guides and the noise will be gone.

Good luck!

[tri again]

I've got the same machine with the same noise.
Intermittent and annoying.
Then it goes away. Idle like a dream, and then click tap for a few seconds just to see if I'm paying attention.

I promised myself I'd get to it now that the weather is not freezing and will keep you posted.
oh and like doug said, try clicking on:

service manual

The tensioners are not real complicated but I think they move out as necessary to take up chain slack and something funny to get them to unload so you can put it back in, surely in the manual.
I took mine out hoping to get an idea of chain stretch, wear marks etc but that was last year.
If I was real serious, I'd be tempted to check the wobble of the rockers too.

[rooster67]

Thanks for the input guys!
tri again,
I have the service manual i downloaded from Oscarmayer. I have damn

near read that thing back to front. I understand that replacing the

chain (if it comes to that) requires removing the engine cap above

the head, removing the right side case and also BOTH clutches, oil

pump ect. I have found at Hyperparts.com they have a gasket kit and

also a chain they sell. I am however concerned about one thing. In

the manual it says that upon removing the external oil pipe that

goes from the oil filter up to the head. The manual says that when

you reinstall that piece to replace the sealing washers. I have

searched ebay and online etc and cannot find these sealing

washers..maybe they come in the gasket kit from hyperparts? Have you

thought of this?

Garrett

[barnett468]

Hello Rooster67


"In the manual it says that upon removing the external oil pipe that

goes from the oil filter up to the head. The manual says that when

you reinstall that piece to replace the sealing washers. I have

searched ebay and online etc and cannot find these sealing

washers..maybe they come in the gasket kit from hyperparts?"



If the washers are solid copper which they probably are you can easily get them from most auto stores in their Dorman parts bins behind the counter, some regular hardware stores and ALL industrial hardware supply stores etc.


Hope this info helps.

[tri again]

copper crush washers?
I got some for a bosch cis injection gas filter from napa.
They were so hard, they leak/sprayed so I used my old ones for a 24 hour run to Canada.

I called napa and they said whatever came with the filter was all they had
but I know they exist.

If / when you pull the tensioner, you can somehow shove a 1/4" extension in there and see how deep it goes .
I really want to believe someone has a service limit measurement for the timing chain and chain rail guides.
If someone has a real noisy OBVIOUS chain engine apart, I would like to beg them to measure the depth from the case to the internal contact point, which I think is probably the chain guide.

That tensioner, as I recall, 'steps' out and locks out to where it wants to be.
If it has another 1/2 inch, or whatever to go, it may mean something.
If it's all the way out, oil stained and obviously has no tension against the chain, it would be Great to know.

I'm either getting lazy or old and simply don't feel like doing a chain if I don't have to.

Lets try to find some measurements.
I'll call my local honda shop and see what they say.

[barnett468]

"copper crush washers?
I got some for a bosch cis injection gas filter from napa.
They were so hard, they leak/sprayed so I used my old ones for a 24 hour run to Canada.

I called napa and they said whatever came with the filter was all they had
but I know they exist."


Hello

I don't quite understand your post. There are both copper or copper "sealing" washers and a copper "crush" washer. Sometimes the terms get switched around. There are solid copper washers which are exactly the xame ones used on virtually ALL motorcycle oio lines and ALL brake hose bolts on every car produced so obviously when used propeely used in the proper application they do not leak. They can rarely be reused with any success. The other type actually have a soft center EXACTLY like the copper exhaust gaskets on your trike exhaust.

I have no idea how your fuel filter worked but if it used banjo bolkts then it would use the hard type. They often need to be "seated" by tightening, loosening slightly, then repeating until sealed. It's a pain.

[Woodsrider]

I was told a trick to verify if the noise is actually coming from the cam chain, however, I have never done this so really can't say if it's a good idea or not, so others can weigh in on this. I was told to remove the tensioner and then carefully push something like a plastic Bic pen into the hole while the engine is running.....the theory being that you will be able to tighten up the cam chain tighter than the auto tensioner will, and if the noise stops while you're doing this test, then you know you need to replace the chain/guides.

[tri again]

I was told a trick to verify if the noise is actually coming from the cam chain, however, I have never done this so really can't say if it's a good idea or not, so others can weigh in on this. I was told to remove the tensioner and then carefully push something like a plastic Bic pen into the hole while the engine is running.....the theory being that you will be able to tighten up the cam chain tighter than the auto tensioner will, and if the noise stops while you're doing this test, then you know you need to replace the chain/guides.

ahHA!

I now remember a thread about some replacement tensioners that are manually adjustable.
Maybe ebay? or some aftermkt supplier.
I'll try the search key.
I've also heard of chains jumping the camchain wheel so I'd be real careful or more likely too scared to run without direct chain tension.

Welp? you guys have me motivated to go work on trikes.

[tri again]

"copper crush washers?
I got some for a bosch cis injection gas filter from napa.
They were so hard, they leak/sprayed so I used my old ones for a 24 hour run to Canada.

I called napa and they said whatever came with the filter was all they had
but I know they exist."


Hello

I don't quite understand your post. There are both copper or copper "sealing" washers and a copper "crush" washer. Sometimes the terms get switched around. There are solid copper washers which are exactly the xame ones used on virtually ALL motorcycle oio lines and ALL brake hose bolts on every car produced so obviously when used propeely used in the proper application they do not leak. They can rarely be reused with any success. The other type actually have a soft center EXACTLY like the copper exhaust gaskets on your trike exhaust.

I have no idea how your fuel filter worked but if it used banjo bolkts then it would use the hard type. They often need to be "seated" by tightening, loosening slightly, then repeating until sealed. It's a pain.

I appreciate what you say for sure.
I worked at a dealership and probably changed a thousand of those filters but the copper washers that came with the filter from napa were copper 'colored' and super hard. almost like copper anodized steel and simply wouldn't seal.
The old ones went right back in, snugged up and perfect.
I just didn't have time to go look for real copper ones.

Yeah, I'd like to see some service limit measurements for chain tensioners and maybe even some sort of measurement for oil flow to the head. either pressure or volume. 1/2 cup in 10 seconds?
The only thing I've seen is clearance measurements on the oil pump rotor to housing.
Come to think of it, I have a 250sx parts engine I can look at.

[rooster67]

tri again you are dang right. OK so yesterday evening i pulled the tensioner off the front of the head to see what was what. The tensioner was pushed all the way out. i took a 1/4 inch long extension and put it up next to the tensioner and marked the depth level. I then pushed the 1/4 inch extension into the head and where the mark was was as far as the tensioner guide would push. I then, (like an IDIOT) turned the engine over for a brief second and i heard the chain jump a tooth or a few. NOW the timing is off and it will run when giving it gas but will not idle anymore. I'm PISSED. went ahead today and ordered a new chain from D.I.D. and also a gasket set. I am going to crack the right case off this evening and start following the service manual to pull the two clutches and oil pump to start making head-way on replacement of the chain. I am also going to examine the chain guides as i have a feelin' those buggers are worn out too. Can anyone verify with me that i will ONLY have to pull the head cap and the side case to replace the chain? i reaaaally don't want to have to pull the head...

* FOR EVERYONE ELSE THAT READS THIS THREAD, DO NOT TURN THAT ENGINE OVER WITHOUT THE TENSIONER BOLTED UP ON THE HEAD.*

By the way, here is a link to the SX we are discussing http://garrettshare.shutterfly.com/pictures/134

Garrett

[rooster67]

ahHA!

I now remember a thread about some replacement tensioners that are manually adjustable.
Maybe ebay? or some aftermkt supplier.
I'll try the search key.
I've also heard of chains jumping the camchain wheel so I'd be real careful or more likely too scared to run without direct chain tension.

Welp? you guys have me motivated to go work on trikes.

Tri Again you are correct about being careful about the chain jumping teeth. I went out last night and pulled the tensioner off and marked it up next to a 1/4 inch rachet extenion. I then pushed the ratchet extension into the hole and pushed in on the chain guide. The guide pushed all the way in and stopped right as the mark on the extenson met the mounting serface for the tensioner, telling me that the tensioner was pushing the guide in as far as it would go. SO i held the 1/4 inch extension in there and tunred the engine over briefly and it jumped teeth and now the bike with crank as long as you are giving it some gas but will not idle anymore. Basically i jacked up the timing completely. I went ahead and ordered a chain from D.I.D. and also a gasket set as well. I am going to take the side case off tonight and inspect, then get the service manual and start removing the two clutches, oil pump, and head cap. Does anyone know for sure that I will only have to remove the head cap and side case to replace the chain? I reaallly dont want to have to remove the head... Also I am going to inspect the chain guides as I am sure they are worn out and need replaceing as well. Here is a link to some pics of the bike
http://garrettshare.shutterfly.com/pictures/134

[tri again]

ouch.

so sorry.
But at least it sounds like it was time for a chain anyway?
so you're saying that the tensioner was all the way out as confirmed by using the 1/4" extension as a depth guide/gauge?

I think mine, if I pull the tensioner out and let it extend as far as it can and then push it back in, there's a space between the tensioner and the case, meaning that when reset, the tensioner still has a quarter inch of throw to go.
Doesn't sound like much so maybe I'm next for the olympic timing chain event.

Pls keep us posted. and x2 on lining up a source for the guide rails in case you need them.
I'd be tempted to check torque at least and or blue locktite.
Man o man, someone here has been through this, I'm sure.
Are you able to access the search key?

[tri again]

Pretty sx for sure.
Just like my little clicktapper.

How come the cute ones always seem to cause the most trouble.

Just think, after this fix it will be great for another 25 years, probably more.

[barnett468]

Hello


When you have your head off spray brake cleaner in the intake port and see if it weeps around valve, then do the same fir ex. If it weeps they need to bev fixed.


free online manuals

http://www.oscarmayer.net/atc/manuals/


Hope this info helps.