radiator cap leak

[cookiedough]

my 98 Valk tourer I changed coolant a few days prior to putting bike up not riding it really much besides around the block a few miles end of November.  I fired it up yesterday after over 4 months witner layup and ran fine for first 3-4 miles until fully HOT and noticed antifreeze spewing out the aftermarket chrome (and old) radiator cap which does NOT have set screw either.  leaking on INSIDE and steaming up as well pretty bad.  Last November checking antifreeze was LOW about 5-6 inches down or more and since end of season changed it right before winter layup knowing not good to be down that low in COLD WI winters.

I know there is plenty of searches found reading up on possibly bending the tabs flat again on radiator cap and/or the radiator rounded part sanding down a bit.  If bending the tabs (I see it is boiling out of the left inside tab right by the small vent hose on inside and did notice it wiggles some not fully seated, if that does not work,  the show chrome new one is only 15 bucks going that route.

However, does the show chrome one need or have a set screw and is that set screw really do anything or is relavent/needed at all?  My other 2001 Valk I/S is OEM radiator cap and has that set screw, but not sure it really does anything important.

Am sure that aftermarket chrome radiator cap is bad but sure hope is not the radiator top housing itself.

[Jess from VA]

I think the Show Chrome radiator trim caps cause leaks on a number of bikes (but not why).  But you may still need to do a bit of careful bending/tweaking of the lips.  First, I'd work for a tight seal with the OE cap only.

I have a Cobra trim cap (and another I have no idea who made it) and I've never had a leak.

[cookiedough]

I think the Show Chrome radiator trim caps cause leaks on a number of bikes (but not why).  But you may still need to do a bit of careful bending/tweaking of the lips.  First, I'd work for a tight seal with the OE cap only.

I have a Cobra trim cap (and another I have no idea who made it) and I've never had a leak.

what is on there now is not OEM cap but chromed one aftermarket.  yah, will try bending each tab (for sure inside tab by small vent tube) since that is where coolant was spewing out once fully warmed up.  The cap does jiggle loosely on the inside seems to be not to tight nor fit well.  Now I know why the radiator fluid was way low in October when I bought it cheap enough.

[Bighead]

Is it a chrome cap or just a cover? I have a cobra on my std .....no problems. And had a show cheome on my IS and it made the cap leak...removed cover and no more problems.....it was pushing the cap down when on .....thats why it made it leak.

[cookiedough]

Is it a chrome cap or just a cover? I have a cobra on my std .....no problems. And had a show cheome on my IS and it made the cap leak...removed cover and no more problems.....it was pushing the cap down when on .....thats why it made it leak.

good question,  I will check later on today.  good point!

so I take it the show chrome one advertised for 15 bucks is just a COVER not the actuall radiator cap?  Makes sense since the Cobra one is over 40 bucks and probably the actual cap.  Read reviews and sounds like a 1994 honda accord radiator cap for 10 bucks works as well if Autozone, etc. has one available.  I think OEM one is 25-30 bucks or so seems pretty pricey if you ask me.  I could just swap caps all the time since sounds like the one on my 1997 honda magna and 2001 valk I/S also are the exact same radiator cap.

[Bighead]

Yes the show chrome is just a cover but the cobra is also but the show chrome one was very tight to put on so had to push it on with force then it must have stuck with the actual cap pushed down a bit. So I removed it then removed actual cap and cleaned the seal and no more leak. The cobra one fit the cap well,no forcing it on.

[Ricky-D]

Careful examination of the cap will reveal it has two sealing responsibilities. One is to seal the system so pressure may be built up for effective cooling. The other is to seal the cap so that the fluid recovery feature of the system works correctly. Naturally it would make good sense to determine exactly from where the leak occurs. You say the coolant level in the radiator was low. This would indicate there is a leak in the pressure holding capability of the system. If it were the cap that is responsible, then the coolant should be captured in  the recovery tank. If the fluid is not being captured then there is a problem with the recovery system. Both systems need a properly working cap to function as required. However I would suggest to look for a possibly clogged fluid recovery hose since a clogged hose can mimic the problems you are experiencing.

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[cookiedough]

Yah, is just a chrome cover wedged on the OEM radiator cap.  NO way getting it off without excessive force is wedged on there over 20 years am sure.

The recovery hose is the small hose on top of the radiator next to the cap and only one going to the overfull reserve tank behind left side cover correct?  I will try removing left side cover and pulling that hose off reserve tank and blowing in to see if AIR comes out of that top small rubber hose next to the radiator cap since fluid is down below the filler neck now about 1-2 inches.

question:  I am pretty sure my 2001 Valk still under cover (will try to get it out of my garage mess later today) having the OEM radiator black cap is VERY tight no wiggle nor movement side to side.  The 98 Valk bad cap can be pushed down still once on about 1/8" easily and wiggle side to side.  That would tend to lead me to push those 2 metal side tabs on the radiator cap IN 1/8" to form a VERY tight seal, agree???  The 2 side tabs on cap are also curved in a slight U shape, is that normal, not flat?  I know there is a middle spring on the radiator cap but that spring can be pushed down a smidge more lending me to believe is not a tight seal, agree?

There should be no freeplay up/down  or side to side wiggling when pushed down on the radiator cap once on correct?  Pretty sure my 2001 Valk OEM radiator cap fits VERY tight no up/down or side to side movement once on.

If I get my other 2001 NON leaking radiator cap out I might try fitting it onto the 98 radiator and test riding to see if it still leaks out of the radiator cap inside part.  I do not see how that show chrome wedged on cover to the 98 Valk radiator cap can have an effect on the sealing properties of the cap itself since all it is is a VERY tight fitting cover.  I can bet if it I somehow able to get that chrome cover off,  the OEM radiator cap on the 98 would be scrapped up and rusted badly am sure.

[Beardo]

I bought a cobra chrome cap cover at Inzane last year, it didn’t fit on properly, so I tapped it on lightly.

It peed coolant on my right side the whole way home. Bought a new OEM cap and threw that chrome piece of garbage where it belonged. No more leak.

[bentwrench]

If your ever in pinch out on the road a cap from a 90s toyota corolla will go right on and seal both surfaces,same .9 bar rating and all..We put one on my bros magna while on a trip and he left it there till he sold it. I tested it on my valk and it worked fine.

PS get a stant cap the others are crap.

[cookiedough]

I bought a cobra chrome cap cover at Inzane last year, it didn’t fit on properly, so I tapped it on lightly.

It peed coolant on my right side the whole way home. Bought a new OEM cap and threw that chrome piece of garbage where it belonged. No more leak.

I am thinking I am going to splurge soon going to HONDA dealer on new OEM radiator cap after ONE more attempt at bending the side tabs down slightly more on the old cap with chrome cover on it now.  I bent  down till level as I could get with needle nose pliers both sides (both side tabs about 1/8" down) and thought I had it good drove 5 miles or so NO LEAKS until I got back  home and GUNNED the 98 Valk up our hill doing 40 mph in 2nd gear, then it started leaking out again on one side darn it yet again!!!  The cap fit tighter with less sloppiness hardly any side to side nor up/down movement freeplay, but still not as SNUG fitting no wiggling at all as my OEM cap with set screw on my 2001 Valk I/S.  Maybe that set screw helps the sloppiness and not having it in is just enough slop since I cannot have that set screw in with the old chrome cover on the cap on mine now.  

Next time out I will just swap my 2001 good OEM Valk radiator cap with set screw onto my 98 Valk and if that one leaks out, then I know it is not the radiator cap, but something else like clogged reserve tank tubing which I doubt it is or bad radiator filler neck which looks fine to me identical to my 2001 Valk radiator filler neck nothing bent or out of the ordinary there.

Sometime the simplest things need fixing can be the most difficult??    
Before last winter right after I bought it, I fixed the bungee corded kickstand with the correct OEM parts which having a bungee corded kickstand is surely not safe going down the road, only for emergency use.  Previous owner never really did much am sure on the bike.

[cookiedough]

read reviews on radiator caps in search engine and went to autozone bought a 1994 honda accord radiator cap for 10 bucks since stealer wanted 32 bucks having to order it as well not in stock of course.  I actually bought 2 different brands since 1 fit and 1 did not each for 10 bucks.  NO LEAKS so far from radiator cap.  Yippee, until got back:

It did NOT leak after 6 mile ride like my OEM one did with chrome cap on top.  However,  coming back last 1/2 mile smelt antifreeze and now on LEFT side UP TOP corner was smoking/burning antifreeze.  I am now thinking is a bad radiator maybe pinhole top left corner was smoking on the inside when shut it off in garage and saw very tiny liquid amount not dripping or running down or anything but a few inside fins had antifreeze, but very small amount on top inside left corner.  I wonder if it could be just residual left from the first 2 short 6 mile outings since when on side stand the Valk tips to the left and it ran down that left side??  Or,  a pinhole leak in radiator fins on top left inside corner.  The front top left outside fins were dry that I saw,    smoke was coming from top left inside corner with just a few radiator fins barely wet.

I guess go for another LONGER ride and see if the radiator smokes antifreeze and radiator cap does not leak when totally super HOT HOT!!! vs. just a 6 mile jaunt in country in back.    

I will also check tomorrow my vent tubing is not blocked going down left side panel and make sure antifreeze is at or near the full mark on reserve tank which is what I filled it up to last November before winter.

Radiator fluid is currently just below the right side top large radiator hose down about 2 inches tops, if that..  antifreeze was FULL to the top last week when went for 2-3 six mile rides leaking out the OEM radiator cap that much in 3 short trips out.

That 1994 honda accord autozone radiator cap sort of worries me though since the 2 locking fins (tabs) on the 2 opposite sides are VERY short like 1/8" is all inward vs. the OEM radiator cap is near 1 cm inward.

[bentwrench]

Did they have a stant ?.I have nothing but trouble with the other brands.

[cookiedough]

Did they have a stant ?.I have nothing but trouble with the other brands.

Stant at Autozone or Honda dealer?  No, Autozone did not have Stant brand was 2 other names instead. 

LIke said,  one 1994 honda accord radiator cap fit nicely no leaks, the other I will return.  Now just thinking radiator on top left backside has a pinhole or leak in it unless the 3 previous short runs antifreeze ran down the right to left side and sat on the few fins that showed liquid.  Going for another longer ride today to see what happens just do not trust it yet to go for more than 10-15 mile rides so far with antifreeze leaking/smoking out of the radiator fins now top left side in back of radiator. 

[cookiedough]

took 98 Valk for longer ride yesterday with 94 honda accord radiator cap and cap was fine.  Is still seeping, although very, very slightly,  from left top in back of radiator thru fins.  Not enought to smoke anymore like did previously, but enough to smell it once is warm.  Not leaking down or anything from inside top left corner of back fins but enough to see some antifreeze residue. 

I guess leave as is or time to replace radiator itself with another used one?  Was smoking pretty badly last time it ran but will keep riding it keep getting longer and longer rides to see if HOT HOT HOT makes it smoke from residue or not coming out back top left of fins.  My guess is will stop seeping once top 1-2 inches of antifreeze gets lower and lower.  When bought 98 Valk last November, antifreeze was down near 1/2 way in the radiator.

[Ricky-D]

Because of that tiny leak your radiator if not protecting the engine properly. You can simply put in a tablespoon of a good stop leak to solve that problem with no ill affects. Some will condemn this repair but when you look at the price of a new radiator or see whats available in used radiators the attractiveness of this repair becomes clearly evident. I made the same repair probably ten years ago for the same ailment and have no regrets. Used radiators are usually salvaged from a wreck and can not be guaranteed to not leak, and besides they're usually misshapen.  The haters will flame away, but this is good legitimate advice, regardless.

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[cookiedough]

Because of that tiny leak your radiator if not protecting the engine properly. You can simply put in a tablespoon of a good stop leak to solve that problem with no ill affects. Some will condemn this repair but when you look at the price of a new radiator or see whats available in used radiators the attractiveness of this repair becomes clearly evident. I made the same repair probably ten years ago for the same ailment and have no regrets. Used radiators are usually salvaged from a wreck and can not be guaranteed to not leak, and besides they're usually misshapen.  The haters will flame away, but this is good legitimate advice, regardless.

***

so,  a tablespoon you think is all that is needed as well as topping off with antifreeze that last top 1 inch since is down that far now from total full.    Besides you, has stop leak worked for others either in car or cycle radiators, never used the stuff.   Weird how a smidge of antifreeze residue is seeping very, very tiny thru the rear fins in back top left corner just enough to see the fins slightly damp is all.

[Ricky-D]

Yes, a tablespoon ought to be adequate. I cannot speak for other's experiences, but I know the product has been proven over decades.

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[Paladin528]

Radiators can be repaired and welded.  Check with a local repair shop.  I have had them done a lot in the past for a fraction of the price of a replacement.  Even a full re-core is cheaper.