GS400 (1981) Oil Leak from Cam-Chain Tensioner

[Guest]

Hey all,

I'm super new to all this so I'm not sure if this is the right place to post or if this is even the cam-chain tensioner.

I have a pretty heavy leak coming out of the base of this bolt. I'm trying to figure out why oil is coming out of here.


How can I fix this? Should I just be tightening the nut on the spring's side?


Any help is appreciated.Thank you!


pics:
https://imgur.com/a/DuXAlhj

[Steve]

The good news is that the parts are available.

The not-so-good news is that there will be quite a bit of labor involved.

At the very least, you will need the gasket between the tensioner and the cylinder block and the three o-rings and seals shown in this diagram. You are looking for parts 14, 15, 16 and 20.

https://www.cmsnl.com/suzuki-gsx400e-1984-e-general-export-e01_model13613/partslist/FIG11.html#.W1FU0GeWz4Y

The problem is that you will need to remove the carbs to gain access to the tensioner bolts. Since you will be removing the tensioner, it is always good to make sure the chain has not jumped a tooth, so remove the valve cover, too. And hey, while you have that off, wouldn't you know, it's the perfect time to check your valve clearances.

.

[John Park]

You often see the phrase, "assembly is the reverse of disassembly". In this case, you disassemble in the reverse of assembly or the cam timing [chain] can slip and then you are in deeper than you needed to be, and a whole lot deeper than that if you try to run the engine with the valves and pistons beating up on each other.

Twins are different from fours, so something that works on fours may not apply.

As I recall, you can get the tensioner off without removing the carbs on a twin. It's a bit tight, but there's more room if you take the starter cover off first. The engine must be in the right position of rotation before removing the tensioner and not disturbed until the tensioner is fully reinstalled.

While it is nice to replace the o rings while you're in there, the main culprit is typically the seal that lives under the spring/knob in the big nut. If you can't easily get the Suzuki seal, you can use a Honda seal - #91259- VMO- 000 which is current. I actually prefer the Honda seal; it works better on old and worn shafts.

Study the manual and take your time preparing before heading in. Better an annoying drip than a laid up bike in summer.

[hugo151]

Mine was the seals inside the tensioner which were leaking, luckily I had a spare engine to rob it off & just bolted the whole spare tensioner back on, don't think there's much chance of the chain jumping a cog, & don't think I removed much to fit it, maybe the starter cover.

[John Park]

Mine was the seals inside the tensioner which were leaking, luckily I had a spare engine to rob it off & just bolted the whole spare tensioner back on, don't think there's much chance of the chain jumping a cog, & don't think I removed much to fit it, maybe the starter cover.

If you place the engine in the position used for assembly, the tension will be on the front run of chain due to the valve spring. The intake cam will be slack with no reason to move on the chain. IOW the right piston should be at top center on the compression stroke.

You might get lucky at some random other position, but there is a REASON the cams and tensioner are installed at the official position. For the time it takes to do it right compared to the time and grief possible from doing it at random, the right way is faster. Having the valve cover off at the time also allows you to see what is going on, plus check the valve clearances.

[leakybreaks]

OK, it looks like I have my work cut out for me. Apparently the service manual for this specific bike is unavailable so I'm told to order the GS250 manual. Once I grab that I'll start studying.


In the meantime, Here's what I think is going on with my bike (beyond the oil leak).

It's not running atm but has been running with blue smoke recently. My oil smells a whole lot like gasoline and my right spark-plug keeps fouling with oil. I think there's something wrong with my valve cover gasket that's allowing oil to seep in to my combustion chamber on the right side. Once that side stops firing, gas sneaks past the piston and gets into the oil tank. Does this sound diagnosed properly?

I think my first step should be to change my oil and get something fresh in there - maybe run some seafoam through it to get rid of nasty deposits. Next step would be to take apart the engine to replace those valve gaskets.

What do you think?

[Steve]

It's not running atm but has been running with blue smoke recently. My oil smells a whole lot like gasoline and my right spark-plug keeps fouling with oil. I think there's something wrong with my valve cover gasket that's allowing oil to seep in to my combustion chamber on the right side. Once that side stops firing, gas sneaks past the piston and gets into the oil tank. Does this sound diagnosed properly?

I think my first step should be to change my oil and get something fresh in there - maybe run some seafoam through it to get rid of nasty deposits. Next step would be to take apart the engine to replace those valve gaskets.

What do you think?

First off, if it is the valve cover gasket leaking, it will NOT leak into the combustion chamber. That would be the HEAD gasket.

Second, yes, it's possible that gas might be getting into #2 and getting past the piston (rings), but a more-likely situation would be that the petcock on the fuel tank is defective, allowing fuel to flow when it shouldn't.

Third, not sure what you are calling "valve gaskets", but it might not be necessary.

What I think:
- change the oil and filter
- replace the o-rings in the cam chain tensioner
- replace the petcock (don't bother with a rebuild)
- replace the spark plugs

.

[LAB3]

Got lucky on my 450 and all it took was replacing the $2 gasket between the tesioner and engine, if that's all there is then it's an easy fix. Give the gasket a try, all you'll be out is the gasket and some RTV if it's one of the seals.

[fastbysuzuki]

Hi have a look at this. http://www.bwringer.com/gs/camchaintens.html. As for the big oring I had a decent battery impact gun but it defeated me If you can't manage to get this loose with reasonable amounts of force, STOP. Don't risk damaging anything. Just leave this part in place -- that o-ring isn't really what's leaking, and you can replace the seal with the shaft in place.

[leakybreaks]

First off, if it is the valve cover gasket leaking, it will NOT leak into the combustion chamber. That would be the HEAD gasket.

Second, yes, it's possible that gas might be getting into #2 and getting past the piston (rings), but a more-likely situation would be that the petcock on the fuel tank is defective, allowing fuel to flow when it shouldn't.

Third, not sure what you are calling "valve gaskets", but it might not be necessary.

What I think:
- change the oil and filter
- replace the o-rings in the cam chain tensioner
- replace the petcock (don't bother with a rebuild)
- replace the spark plugs

.

Thanks for this - yes, I guess I mean head gasket.

Last time I took apart the carbs the petcock didn't seem to be faulty but I'll check again. It's probably similar to many GS bikes but there is no off position, just ON, RESERVE, and PRIME. If need be I'll definitely replace that.

In regards to the oil fouling my plugs with the faulty head gasket... does this seem as straight forward a fix? I've never taken apart the engine but I'm definitely willing to learn. Just curious as to what I'm getting myself in to.

[Gorminrider]

Apparently the service manual for this specific bike is unavailable so I'm told to order the GS250 manual. Once I grab that I'll start studying.

If it is an 81 400 in Canada it is a "gsx" engine. The cam end covers are square. These are GSX engines ie: 4 valves per piston. Haynes publishes a manual for these bikes..available or can be ordered at Canadian Tire about $20

The pdf shop manual for download is at BassCliffs. You also want the addendum which describes differences of the 400s.

http://zeus.mtsac.edu/~cliff/storage/gs/GS250T-300LZ_manual-82.pdf

http://zeus.mtsac.edu/~cliff/storage/gs/GS400_Complete_Manual.PDF