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Discussion Starter · #1 ·
Hi,



Whilst doing a routine tappet check today I noticed a small amount of custard in both the rocker covers, not a lot but enough to get me thinking, then I noticed the coolant overflow bottle was nearly empty so topped that up and went on to check the radiator, that was slightly down too, oil on dipstick looks clean and level is normal, it's only about 1000 miles since I replaced the mech seal and there is no evidence of any coolant leaking from the seal (Unless its going internal, but the drain hole was clear when I changed the Mech Seal). Now I'm wondering if an head gasket may have gone and most of the coolant has burned away as if all that coolant had gone into the oil the contamination would be much more evident,



Before I start stripping down I wondered if a compression test would be any good for checking head gaskets - any advice will be much appreciated.



Regards



Longway
 

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Hi,



Whilst doing a routine tappet check today I noticed a small amount of custard in both the rocker covers, not a lot but enough to get me thinking, then I noticed the coolant overflow bottle was nearly empty so topped that up and went on to check the radiator, that was slightly down too, oil on dipstick looks clean and level is normal, it's only about 1000 miles since I replaced the mech seal and there is no evidence of any coolant leaking from the seal (Unless its going internal, but the drain hole was clear when I changed the Mech Seal). Now I'm wondering if an head gasket may have gone and most of the coolant has burned away as if all that coolant had gone into the oil the contamination would be much more evident,



Before I start stripping down I wondered if a compression test would be any good for checking head gaskets - any advice will be much appreciated.



Regards



Longway
its summer,you said your rad level is down a little,1000 miles.thats normal.

change the oil and filter,top all your fluids up[better still,]service the cooling system,and top up.then monitor

on what you have said,id pull nothing yet.

dont imagine what might or might not be happening
 

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forgot to ask......when did you change your oil last?
 

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Yes, a bad head gasket will almost always show on a compression test. Its sure worth a try as its a quick fast test, and will help put your mind at ease. Sometime you can get a custard buildup in the rocker area from moisture, especially if the cover seals are leaking (if the center seal in the plug hole leaks it can let water in). If your dipstick shows nothing but clear oil you are probably fine, especially if the compression test shows normal.
 

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Discussion Starter · #5 ·
Cheers for replies, I will do a Compression test and unless I get a bad reading will not start stripping just yet, the oil and filter was changed with Mech Seal about max 1000 miles ago, there has been no signs of overheating, last time I took it out did couple of 100miles at 6-7000 rpm, bit more than I usually ride at



Also to add the engine is running OK and ticks over OK, it doesn't feel like it's losing any compression
 

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As above and to add.Change the Rad cap and the thermostat and doing a cooling system flush,



Click here,

http://www.pdsrecording.site90.com/cxgl500/Coolant.htm



Some Milky slime in the heads can also be caused by the storage conditions the bike has been in and moisture getting into old oil and also a dirty Air-box.



You can take the Rad caps and thermostats to a decent car parts suppliers and get them to match them up and get both for less than the cost of one single so called,"Honda" part.











For the Air-box.Remove filter and it's small dais.Remove overflow pipe plugs and boil up several kettles of water and squeeze some washing up liquid into the box and move around with a brush,then pour boiling water into it to clean and flush.Dry out and re-fit.I only have to do this every other year as they can get a build up of oil vapor from the engine oil breather system.This will prolong the life of the Air-filters.

If the vanes of the Air-filter are in good condition they can be petrol/gas soaked and high pressure blown out and re-used.
 

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Discussion Starter · #7 ·
Thanks Shep, I have now ordered a new air filter, since the one fitted is about 5 years old (10000 miles)



Took breather pipe off and blew all the gunge out, will give airbox thorough clean out when I get chance and check compression, bike is stored in a nice dry timber shed
 

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There`s some pretty big clues there that point to something amiss - loss of coolant from the expansion bottle and mayo in the valve covers. Recent pump seal...

You can`t ignore the fact that those could be related..

It`s not normal for mayo to form inside the valve covers except maybe in some extreme conditions which don`t appear to apply to you or your bike.



When you did the water pump seal did you do it with the engine still in the frame or removed?

Was the camshaft oil seal replaced? (this`ll be dependant on whether the engine was removed when you did the pump seal)




When CX head gaskets go the coolant usually finds it`s way out of the exhaust pipe or expelled from the expansion bottle - not into the crankcase, with a corresponding loss of coolant in the res. and rad.

A compression test may be helpful if it detects a large enough difference between one cylinder and the other but quite often CX test results are are too vague/low to pinpoint a defective gasket, and figures anywhere between 120 - 145psi are usual. Your small (ish) coolant loss over 1000 miles (if it was a head gasket) may not even show up on a compression test.



I`m thinking there`s an issue in the water pump area.....
 

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Discussion Starter · #9 ·
I did a compression test yesterday and both were equal at 140, bike seems to be running well, tickover is even, temp gauge at nornmal



When I replaced Mech Seal, I removed engine, replaced camshaft oil seal and copper washer, also replaced the O rings for waterways - is it possible one of these O rings has got nipped I wonder? there is no coolant from mech seal drain hole, although I will double check it isn't blocked
 

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I refer the right honourable member to my previous reply.I don't think you have anything to worry about but just re-check inside the head covers after a few rides and see what the deal is.I've had a bit of custard in them if I have been working away for several months and then got my bike/s out of my cold-and-damp-in-winter metal garage.Just do some general cleaning out of the breather pipes/Airbox etc.People tend to forget these things
 

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Discussion Starter · #11 ·
Last night I clocked up another 50 miles and I've just been in the shed to find the water level in the over flow bottle has dropped around 1 inch, also taken rocker covers off to find more custard and also drops of clear pink coolant which appears to be coming the flat headed stud as arrowed in photo







Will this be the Head Gasket?
 

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Will this be the Head Gasket?
could well be.a compression test might well not confirm a blown head gasket.

or,it could be a problem with the mech.seal.

its a call.......you know you did work around the pump...its a hard call
 

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When I replaced Mech Seal, I removed engine, replaced camshaft oil seal and copper washer, also replaced the O rings for waterways - is it possible one of these O rings has got nipped I wonder? there is no coolant from mech seal drain hole, although I will double check it isn't blocked


OK, when you installed the oil seal did you ensure that it only went in as far as the engine casing and was level with it?

ie; you didn`t push it down so far that it backed up against the rear of the water pump seal and obscured the weep hole?



If you used some silicone sealer around the cup could some of blocked the weep hole?

That`d take a of a lot of excess sealant so is unlikely, but you never know....



There`s only two usual places where coolant can get into the oil on a CX (ignoring the rear cover o-rings that go around the water transfer dowels - i`ve never heard of one leaking, any coolant would also have to get past the rear cover gasket); the water pump or head gaskets.

Process of elimination.

If you`re absolutely 100% sure on the installation of the pump seal it does point towards a head gasket.

That large bung in the head is (i think) a remnant from the casting process during manufacture and the small amount of coolant around there may just be because it`s recessed slightly and allowed the water to collect there. It`d be extremely unusual for one of those to leak. Have a poke at it with an allen key - see if it`s loose?

If you want to eliminate the water pump there is a relatively easy way to check the weep hole isn`t blocked while also checking out the rest of the pump/seal/nut area.

Remove carbs/water pipe/pump cover.

Is the dome nut still nice`n`snug?

Remove impeller.

Ceramic/washer/seals all OK?

Get a can of WD40 or similar (nothing too agressive) and poke the end of the straw into the weep hole entrance.

Seal around the straw and where it enters the case with some Blu Tack.

Squirt.

If the weep hole is clear the WD40 will exit via where the camshaft goes through the seal (once enough WD40 has filled the void).

If it forces it`s way back outta` the casing or doesn`t squirt it`s blocked...



If the weep hole is clear, any coolant as you say would have tricked out if there is an issue with the pump, so that`s that area eliminated.





Clues to head gasket failure:



Whiff of petrol in the expansion tank

Coolant expelled from expansion tank overflow hose - especially when stopped after a long run

Bubbles in expansion tank

Bubbles in rad.
 

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Discussion Starter · #14 ·
Just inserted a thin plastic tube which comes with the WD40 cans without any resistance into the mech seal weep hole and compared the distance inserted against another rear engine cover it goes in the same distance without any resistance hence I don't think there any issues with the drain hole being blocked



There is no smell of fuel in the overflow either - now what? head off or engine out and rear cover off its a tough call
 

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- now what? head off or engine out and rear cover off its a tough call
no,thats not a tough call.......pull the heads,service the top end,lap valves,de-coke..

here was my heads on a good running engine









wipe over



 

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now what? head off or engine out and rear cover off its a tough call


OK, seems like all is well in the water pump area.



I don`t think you`ve had this bike too long, have you?

Is there any reason for you to suspect that the previous owner had the heads off or fitted new gaskets just before you got it?

Or, did you have the heads off when the engine was out?

Try re-torquing the head bolts, if they move much that`s not a good sign.



Bandit, how is lapping the valves and a `decoke` going to solve a loss of coolant?

And it is a tough call, the owner has already had the engine out recently and the last thing he want`s to do is remove it again if at all possible, especially if the fault isn`t cured and unecessary work is carried out, so trying to identify the coolant loss at source rather than guesses is the way to go.



Shep, read the thread - a compression test has already been done: 140 both pots.

Whether the oil seal was fitted the right way or not, there shouldn`t be any coolant that side of the pump seal anyway, and the weep-hole appears to be clear.



Longway, that coolant around the head bung does look a bit suspicious...

It looks `fresh`, uncontaminated with the oil, not yet formed into mayo.

Unfortunately it looks like you can`t get a key in there or inspect it because the rocker gear is in the way?

Can you get hold of a coolant system pressure tester?

Putting the system under pressure might give a clue as to where it`s leaking from.

Unless you`ve got an odd fault like a cracked head (or that bung) there`s not many options left..
 

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Discussion Starter · #18 ·
Do a compression test as above.Also when you fitted the Water pump Oil seal id you fir it the correct way round?


did compression test yesterday, 140 each side and I'm sure I put the seal in correct way round and just flush with engine case
 

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The fact it's in droplets in those pictures and not mixed with the oil is a little strange so it's got me stumped at the moment.Is there any coolant leaking down from around the Thermostat housing and coolant transfer pipes?



I do recall some years ago that some one had a cylinder head problem whereby the large Allen bolt in the head(Factory fitted and not meant for us to touch) had worked loose or an attempt by a PO to remove it had loosened it but that seems unlikely.
 

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Discussion Starter · #20 ·
OK, seems like all is well in the water pump area.



I don`t think you`ve had this bike too long, have you?

Is there any reason for you to suspect that the previous owner had the heads off or fitted new gaskets just before you got it?

Or, did you have the heads off when the engine was out?

Try re-torquing the head bolts, if they move much that`s not a good sign.



Bandit, how is lapping the valves and a `decoke` going to solve a loss of coolant?

And it is a tough call, the owner has already had the engine out recently and the last thing he want`s to do is remove it again if at all possible, especially if the fault isn`t cured and unecessary work is carried out, so trying to identify the coolant loss at source rather than guesses is the way to go.



Shep, read the thread - a compression test has already been done: 140 both pots.

Whether the oil seal was fitted the right way or not, there shouldn`t be any coolant that side of the pump seal anyway, and the weep-hole appears to be clear.



Longway, that coolant around the head bung does look a bit suspicious...

It looks `fresh`, uncontaminated with the oil, not yet formed into mayo.

Unfortunately it looks like you can`t get a key in there or inspect it because the rocker gear is in the way?

Can you get hold of a coolant system pressure tester?

Putting the system under pressure might give a clue as to where it`s leaking from.

Unless you`ve got an odd fault like a cracked head (or that bung) there`s not many options left..


This is the red CX500A that I've had since 2005, Eurovee, I'm sure you've seen this bike on more than one occasion



I've never had the heads off and its clocked up around 10,000 miles in my possession, it's strange how the coolant is fresh, I would have thought the source must be very close, the right rocker also has some mayo but no signs fresh coolant



Is that head bung actually screwed in or is it just part of the cast? my first thoughts were to tighten this up but that would be too easy



No I don't have a coolant pressure tester
 
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