Coolant leak

[RedexRobB]

How much coolant have you got in the expansion tank? If you have overfilled it, like right upto the cap, it will more than likely overflow. There are two filler marks on the expansion tank underneath the filler cap, there should be a gap in the infill panel where you can see, check it. If its quite near the top mark i would empty a little bit and see how it goes.

[ross59]

I have to fill my bike up with coolant every 100 miles or so, is this normal??? It comes out the overflow on the expansion bottle when stationary but is barely noticable. The cap on the expansion bottle isn't the right one as it fell off an i have been unable to find a replacement yet could this cause an issue as it doesn't seem to be sucking it back like it used too? I have checked for the obvious signs of the head gasket going but all seems ok. :smt013

[masterofinsanity]

is the bike overheating? have you got the coolant mixture right and is your thermostat seized?

[ross59]

Not sure about the thermostat will have a look it, what's the best test? Doesn't overheat when going along but if I get to traffic the fan rarely kick's in which causes issues. The coolant mix is correct.

[masterofinsanity]

zxr400s usually have to get quite hot for the fan to kick in, test your fan would be the first test, make sure its working, if you pull the wires off the fan switch and bridge them with some spare wire the fan should kick in, just keep away from the fan!

[ross59]

I have tested the fan and it works fine, i also cleaned the conection. It still doesn't come on though when the bike gets over the 3rd notch 2/3rd's of the way up or higher!! Any idea what could be causing this?

[ross59]

One thing I fought to metion the other day it started to run on 3 cylinders then cleared up minutes latter and hasen't done it since was just after i changed the throtle cable. Was thinking head Gasket is on its way out or am i just been paranoid????

[masterofinsanity]

could be a faulty temp sensor, if the bikes not overheating and there's no signs of head gasket going why are you worrying? change the temp sensor and see what happens.

[Caz]

I have to fill my bike up with coolant every 100 miles or so, is this normal??? It comes out the overflow on the expansion bottle when stationary but is barely noticable. The cap on the expansion bottle isn't the right one as it fell off an i have been unable to find a replacement yet could this cause an issue as it doesn't seem to be sucking it back like it used too? I have checked for the obvious signs of the head gasket going but all seems ok. :smt013

sounds to me like you have a leak in the system. Im assuming that the bike isnt pissing coolant, so it is possibly caused by the incorrect reservoir cap? the coolant circuit needs to be a sealed system, if it isnt sealed you run the risk of coolant evaporating when the bike gets hot.

Id get the correct reservoir cap on asap and then see if you still have a problem, and also check that you have no air in the system. That could be another reason for you having to top the coolant up every 100 miles or so

[littleninja]

I hate to say it mate but sounds like head gasket to me! Mine was doing a similar thing to yours, fine when going along but started to heat up when stationary, never overheated mind. Coolant was also running out of the overflow pipe. The fan would work fine when i had topped the coolant up but didn't seem to switch on after some coolant had come out of the overflow pipe, i'm guessing the rad must empty itself passed the temp sensor and it causes it not to switch on. Bike used to run fine, no mayonaisey looking oil etc.

Anyway not to waffle on too long , had the head off my bike and bugger me the head gasket had gone in three places!!

For the sake of the price of a gasket (13quid or so!) and a bit of labour, two days for a novice like me, you can have trouble free riding again!

[Haggis]

Looks like I'm suffering from something similar.
I've only had the bike out a couple of times so far, but twice I've noticed that I've had boiling water blowing back into the reservoir.
I have no foam visible in the oil level window.
I'm not blowing white (or black) smoke from the exhaust.
On the Sunday morning pootle I couldn't get it to rev past ~12,000.

I had the top off and the carbs out over the weekend.
I noticed that the plugs were very sooty (but dry).
The carbs are spotless (running standard jets 25/95 with standard needles N77S) and all seems to be in good order (free movement of the slids and butterflies, no tears in the top seals and no blockages).
My feeler gauges need to be replaced as they are not accurate enough, but I checked the tappet clearances and found that the inlets are all .10 > .15 (should be .12 > .17).
The exhausts were all .10 > .15 with the exception of #2 of pot #4 which was .15 (should be .17 > .21)
So the inlets may be OK, but the exhausts are opening for too long, too early and too late. This could cause the plug fouling. I swapped out the standard CR9s for gold/palladium ones with the intention of upping them to iridium ones at some point in the near future.
The can is a Blue Flame which you could hardly call restrictive.

The cam belt was replaced (we're told) about 300 miles ago. There is wet oil on the front of the barrels. So the next step will have to be to strip the plastics off again, get the bike spotless and run him up to nice'n'hot temperatures to see what happens next.

I know of a bloody great mechanic in Twickenham, but he is a bit pricey. I may just bite the bullet and take the bike to him, get him to replace the shims and balance the carbs. Might get a head gasket for him to replace while he's at it.

Anyone know where I can sell a kidney?

[RedexRobB]

The oil at the front of the barrel may be from the spark plug holes. If the seals round these holes leak, the oil will run down to the plug and through a hole which leads to the front of the engine, so be aware it may be that rather than the head gasket.

But going from your other symptoms it could be the gasket anyway.

[Haggis]

The oil at the front of the barrel may be from the spark plug holes. If the seals round these holes leak, the oil will run down to the plug and through a hole which leads to the front of the engine, so be aware it may be that rather than the head gasket.

But going from your other symptoms it could be the gasket anyway.

I did notice the plug threads were wet with oil, so when I re-built it I blue Hylamar'd the guides top and bottom.

[ross59]

Couple of things. Does anybody know of any decent manuals as i have been unable to find any haynes ones (which got me through my car days!)? Has anybody got any useful links on doing a head gasket on a ZXR 400 as i haven't done one before? Cheers

[carsounds_dan]

have you tried the workshop manuals on http://www.zxrworld.co.uk
if you look at the H ones, the L ones just add more information, but the H ones have more details.
im going to do mine over winter so i'll do a write-up on it, it does mean dropping the engine out though.
cheers
dan