Coolant cold leak... Yes one more!

[Elmobile]

In fact I have 2 issues with my 1990 GL1500 SE (180K kms).
Gas consumption is higher than it should with a lack of power and as I found out this winter a more pronounced coolant cold leak which has been there since day one but got really bad this winter.
I decided to tackle both issues:
For the gas mileage, I want to check the engine temperature sensor on the right manifold and also check the ignition bobbins and plugs wiring (New plugs with less than 2K kms). The carbs and vacuum lines have been checked, fixed and rebuilt with no effect on my mileage...
I also wanted to replace all the O ring on the water pipes: the ones going into the water pump and the ones going into the manifold/thermostat.

I went ahead and removed both radiators and fans so far. Now I have good access to the temperature sensors and the ignition wires.
Doing so I believe that I came across the cold leak. It is the water pipes between the engine block and the pump on the left side. Fairly easy to get to. The other side is definitely dry and looking through the maze of pipe under the intake manifold, I cannot see ANY signs of leaks. I am quite sure of that on the right side and the left one seems dry as well.

After all of that, to my question: I have all the seals/O rings but should I go ahead, removed the carbs (Again) and disconnect most of the pipes, remove the thermostat OR should I simply replace the O ring that I know is leaking?
I do have access to check most of the electrical related to the mileage as it stand!

You know what they say, why fix it if it ain't broken...
Looking for the opinion of those who have been there before.
Riding season is not quite there yet for us in Nova Scotia, Canada and we are to stay home anyway... So I have the time to do the work but would hate to make it worse than it is.
What would you do...!

[Elmobile]

Went out to the shop to remove the water pipe on the bottom left side of the engine.
I can kind of wiggle it but it is not moving out. I even moved the manifold out of the way to have more room to no avail.
Any suggestion? no much room to get a good grip on it...
Thanks

[ct1500]

There is a pipe that goes on top of engine to left head?
The pipe itself has a hold down bracket bolt to top of engine. Remove the two bolts from thermostat housing one each side. Then push, pry housing forward to disengage from the two coolant pipes. Replace O rings on pipes and prior to insertion back into housing give them a light coat of silicone spray to aid installation.
Pressure test cooling system prior to putting fans back in.

[Elmobile]

Thank you for the reply ct1500.
The pipe I'd like to remove is #5 as per fiche Water Pump. The O ring I'd like to replace is #10.
https://www.hondapartshouse.com/oempart ... water-pump
It is located on the bottom left of the engine block, behind the exhaust manifold.

I did put everything back together for now and I am going to do a pressure test. It is the advise you gave on another post for a similar problem. If it had come out easily, I would have replaced it. But considering it is going to fight me, I want to confirm that it is the origin of the leak!

Talking of pressure test, now that it is drained, would you refill the system or can I do it without coolant in it? I would have to spray soapy water and look for bubbles instead.
The pressure for the test: 15 to 20 psi? Correct?
Thanks

[DenverWinger]

Per FSM the 1500 radiator caps are rated 11-15 PSI, I wouldn't exceed that, you could create more leaks that weren't there to begin with.

You could just refill with water for the test, and add some of that leak detector stuff that glows with UV light. Your local Auto Parts is likely to have both the a little bottle of leak detector and a UV Flashlight to find it with. Put the leak detector in first, add water, run engine until nicely warmed (fans cycling) to mix it.

[minimac]

IMHO and experience, if one O ring started to leak, chances are, the others will too, and most likely, when and where you can least afford it. It may be a pain, but do them all at once. Do you really want to go through this again?

[fnickel]

I would agree with the latest comment. If you are already that far down in the engine, I would recommend doing all the o-rings while you are down there, even if it is a little more work right now. If you don't replace them now, they could start leaking in another year or 2, and then you're looking at doing the teardown all over again. If the bike lasted this long on the original o-rings, your replacements should be good for another 20 years at least, probably plenty long enough for your use. Also, I remember reading somewhere that the cooling system is a "low pressure" system, so it may not have the same pressure requirements as a typical automotive engine. I'm looking at replacing all the 0-rings in the coolant tubes in another year or 2, as mine are leaking worse each winter. Once summer comes around and the bike is ridden regularly, the leaking stops. I should have done it 2 years ago when I renovated the carbs, but I was in a hurry to get the bike going again in spring.

[ct1500]

I now see it is the pump outlet side. Give it doses of penetrating spray and twist, pry and pull till free after bolt removal. Might be easier to remove with hose still attached, pulling on it too.

[Elmobile]

Thank you for the advice and word of encouragement,
The temperature sensor came out easily with the right radiator and fan out of the way. I will test it today.
As I said I will do a pressure test first and then will remove the carbs and get to the thermostat and water pipes.
I also have the gaskets for the intake manifolds, so they will probably come off as well to have more room to work of the tubing under them.

Let you know how it progress...
Cheers.

[Elmobile]

The engine temperature sensor itself checked good. Well within the specs.
I still have to check the wiring to the ECU to call in it all good...
I decided to put the radiators back on to do the pressure test and also wanted to do a spark plugs check.

Well even so the bike had been stored since October, it started just fine.
Come to realize that the cross over tubing between the 2 radiators is split. Not sure if it was like that before hands or if it did happened while I was working on it. It is the connection on the top of the right radiator. The only one that I did not pulled out. For sure no pressure test until it gets replaced... It was so hard, dried out that I knew it would have to be replaced anyway. Should I get one from Honda or is there a standard size which will fit?

Something strange happen during the spark plugs test. The idle rpm dropped for 5 of the cylinders but not for #2 with no "cracking" noise as compared to the others 5. I then decided to swap the spark plug between #2 & #3 just in case it would the spark plug itself. Unlikely as they are brand new. After that I did pull the spark plug cables again and #2 seems to be fine. Not sure what that means. Can it be false contact in those cables? I am going to ohms them and see what I get. For a minute I thought that I found the cause for my poor mileage.
What needs to get out of the way to reach the ends on the bobbins ends? The fans are still out and I am going to have removed the radiators again. Will that give me access to the ignition bobbins?
Cheers.

[Elmobile]

Did check for the cross over hose on the Babbitts fiches. Looks like the hose is Diameter 7.5 mm bulk fuel hose.
Would a 5/16 (7.9 mm diameter) hose fit? I replaced the 2 clamps as well for sure.
Thanks.

[Elmobile]

Small correction.
The cylinder misbehaving is the #3, the middle one on the left side...
Not that it changes anything at this point...

[ct1500]

Did check for the cross over hose on the Babbitts fiches. Looks like the hose is Diameter 7.5 mm bulk fuel hose.
Would a 5/16 (7.9 mm diameter) hose fit? I replaced the 2 clamps as well for sure.Thanks.

5/16 is the best alternative to metric. I use Gates.
https://www.oreillyauto.com/detail/b/sa ... 08/4348895

[ct1500]

Small correction.
The cylinder misbehaving is the #3, the middle one on the left side...
Not that it changes anything at this point...

Yes it does. That cylinder is the #4 as sitting on bike and it has one, possibly two vacuum ports, one horizontal and one possible vertical for your year. Vacuum leaks downstream in the hoses/components would show as a weak or dead cylinder during a power balance test. Remove that one plug wire from the coil by unscrewing it. Look for a hollow or partially burned out core which for the age of your model would not be uncommon after OHM checking.

[Elmobile]

Thanks CT1500
I looked for the cylinders numbers on the service manual but could not find it. I know it is there somewhere but go find it when you need it...
If #4 is the middle left then #1 is the front right?
Found 5 ft of 5/16 fuel hose that I bought to check my fuel pump flow. Will do that this afternoon or tomorrow (pump check).
I'll definitely checked the wire connection to the coil and report I find a bad connection. I am going to ohms the secondary circuit before. What the best way to get to this coils. The manual says to remove the carbs but could I do it if the radiators are off?
Thanks

[Elmobile]

Well CT1500, must say, you nail it!
It was a vacuum leak as far as #4 is concerned. When I removed the radiators I un-hooked the vacuum reservoir and forgot to plug it back to do my plug test. #4 is now singing as loud and clear as the other 5. The good thing is that when I first un-pugged it, even so the bike had been sitting for near 6 months, there was still a lot of vacuum left in it. For sure no leaks in that part of the circuit..
Did check the coils this pm:
1-2 = 23.2
3-4 = 23.5
5-6 = 22.0
All well within the specs...
I also check the fuel pump and it is fine as well with close to 3 times the minimum flow.

Which make me think more and more about a timing issue. That is what the service manual point to in case of poor mileage.
Before I go ahead and buy a timing light to check that, I know that there is an after market timing wheel (+4Deg I believe).
Would anyone tell me how I could identify if I have one on my bike or if I've got the OEM?
Cheers.

[Elmobile]

I think I diverted too much from the initial subject so I will open another thread as far as my mileage is concerned...
I will do my pressure test as soon as I get some new clamps for the cross over hose and let you know what happen then.
Thanks for the great advice so far.

[TwoTone Trike]

Sorry I can't help you. I just wanted to say that's a cute picture of your pooch.

[Elmobile]

Thank you TwoTone Trike.
Yes he is a good boy. It does look a lot better on that picture than today. Time to get to the groomer... Not sure when that will be
Stay safe,
Cheers