Coolant Pouring Out ? Next Steps

I got the pressure tester and did the test. When I pump it up to 16-20 psi, it immediately starts dropping. After about 25-30 seconds it's dropped completely to zero. Obviously this is not what I wanted to see. I see some dampness on the radiator; everything else looks dry. I decided to ?test the tester? by trying it on my car and it behaves similarly. When I pump it up to 16-20 psi it starts dropping. If I pump it up to a much lower value, it holds. I'm not sure how to interpret this and whether I should trust the results.

I think it's pretty clear I need to take the radiator off and have it tested, but before I spend hundreds of more dollars repairing or replacing it, I think I should put the carbs and airbox etc. back on and make sure nothing was damaged during my ten or so miles of riding with no coolant.

One more bit of information ? when I first got the bike and took the plastic off to do routine maintenance, the cap on the overflow bottle was off. I didn't think much of it (okay I was a little suspicious) and put it back on. Thinking about it now, it may be that the previous owner left it off to prevent leaks because it wouldn't hold pressure.

I assume you are talking about the coolant overflow bottle. If so, there should be no pressure in there anyway as it is vented to atmosphere. Probably just forgot to put the cap back on or didn't get it on all the way and it flipped off. I think I would get another loaner tool and check your cooling system again. If the tool you have is dropping pressure on car and bike, I wouldn't trust it. I once got one from Advance that must have had 20 different adapters, and none of them would seal well on the particular car I was working on. I got one from Auto Zone with 2 adapters and it worked great. It is never a good idea to pump it much higher than the value of your radiator cap though. (i.e. 7 psi or 16 psi, what ever it is, I don't remember on the ST.)

I got another tester and it's holding! Well after five minutes or so, it may drop a psi or two but it seems good to me. It's a big relief because I was looking at hundreds of more dollars to fix the radiator. I couldn't get a good test on the cap (won't hold pressure), so I'll need to replace it. Now to put everything back together....

JPrieST said:

I assume you are talking about the coolant overflow bottle. If so, there should be no pressure in there anyway as it is vented to atmosphere.

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Of course, DOH! :banghead:

Keeping my fingers crossed for you! Your cooling system was in a little bit worse condition than you thought, but a cooling system overhaul on a bike of this age is par for the course. I'm going to get mine done this winter.

Are you going to the WVA traveling rally this year?

jspringator said:

Keeping my fingers crossed for you! Your cooling system was in a little bit worse condition than you thought, but a cooling system overhaul on a bike of this age is par for the course. I'm going to get mine done this winter.

Are you going to the WVA traveling rally this year?

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Thanks Jim. I think you'd be wise to have it done preemptively. Those hoses under the carbs take a beating because of all the heat.

I've thought about going to the rally but haven't been back on the Nighthawk forum since the crash. Are you going?

I tried to get a replacement radiator cap. I couldn't get a good test on it and I'm not convinced the test I did get was valid. I went to O'Reilly, Auto Zone, Napa, Advance and even a bike shop. I gave them the Gates 31336 and Stant 11233 numbers. from the tip page Only O'Reilly had a cross reference for the Gates number but it had "wings" on it so it wouldn't clear the frame to close it. I'm going to reuse the old one until it gives me trouble; I'm in no hurry to pay Honda $32 for a new one.

Try this for radiator cap. Napa part number BK 7031406 or have them look up a 1994 Honda Accord with 2.2 liter engine. That is working for me the last 4 years.

I got everything back together (except the body work).

Hopefully tomorrow, It'll start up and I can see how everything sounds and looks.

JPrieST said:

Try this for radiator cap. Napa part number BK 7031406 or have them look up a 1994 Honda Accord with 2.2 liter engine. That is working for me the last 4 years.

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I went to Napa and they said it was an obsolete number. They tried to match the 94 Accord but everything had the wings. I guess I'll order one next time I order parts on line. At least it's $22 rather than $32.

Good to know that one is obsolete. A quick search on Amazon shows that this one should fit. I can't guarantee that as I have not actually seen and tried it.

Stant 18233

http://www.amazon.com/Stant-18233-Performance-Radiator-Cap/dp/B000CKRNCG/ref=au_pf_ss_12?ie=UTF8&Make=Honda%7C59&Model=Accord%7C751&Year=1994%7C1994&carId=001&n=15684181&s=automotive

Anyone else have any comment on this one?

SHE'S ALIVE!!!

I got it started today and everything seemed normal. I let it sit running in the driveway, then took it for a short ride around the neighborhood and all seemed good. It looks like I dodged a bullet on this.

Before I put all the body work back on, I want to confirm the fan is working properly. When the bike was running sitting in the driveway, the temp gauge was a little more than half, but the fan didn't come on.

I tested the fan motor by jumping the connector wire to ground, then turning the key on, and the fan came on.

What does the temp gauge read when you hear the fan come on? According to the Clymer manual, it comes on between 208 and 216 degrees. I suppose I can just let it keep running in the driveway until it comes on, but maybe it needs to be a hot day. Lately it's been unseasonably cool around here.

Mine comes on just before 3/4 of the way to the red.

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RobbieAG said:

I got it started today and everything seemed normal. I let it sit running in the driveway, then took it for a short ride around the neighborhood and all seemed good. It looks like I dodged a bullet on this.
What does the temp gauge read when you hear the fan come on?

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re: bullet dodging - I didn't want to be the pessimist, but when you said you rode the bike as far as you did with no coolant, I was a bit concerned. However, years ago a woman I worked with gave me a ride home in her Honda Accord. About 20 minutes into the ride home I pointed out that her coolant gauge was pinned to the "H". She said "yeah, it started doing that a week or so ago". Got home and popped her hood to find a blown hose and zero coolant in the car. Duct taped the blown hose and filled her back up with plain water, then she got it fixed and nothing was damaged. So given that the ST is an all-aluminum engine I was kinda thinking you had a fighting chance (aluminum heads on iron blocks are more sensitive to overheating because of the dissimilar expansion rates of the two different metals).

re: ST temp gauge and fan activation

In a good system it should come on just past 12 o'clock on the temp gauge, but if it takes up until about 3/4 of the way to H don't be surprised depending on the condition of your cooling system.

dwalby said:

So given that the ST is an all-aluminum engine I was kinda thinking you had a fighting chance

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Dunno... friend of mine had an unseen leak in "the valley" on his '96, discovered quite late once the 40A alternator blew its brushes and collector to pieces due the coolant seeping over it.
(Living and working in proximity of the m/way, the temp gauge never got a chance to alarm him about the issue of low coolant...)
So alternator and internal passages (including the elbows) got fixed, but guess what: like 3~4 weeks after the repairs he noticed coolant boiling out the expansion tank... LHS head gasket blown...
While at it anyway we then replaced both head gaskets and gave the rig a detailed overhaul to be sure having covered it all; no issues since.

In a good system it should come on just past 12 o'clock on the temp gauge, but if it takes up until about 3/4 of the way to H don't be surprised depending on the condition of your cooling system.

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I tend to agree there; latest at a [12:10hrs] position of the pointer the fan clicks in, and stops at the [11:50hrs] indication...
Any higher temp readings would/could be indication for low coolant level, since the temp probe isn't submerged anymore...

However could the gauge also simply be "off", gauge mechanism defect, improper temp probe resistance, connectors/cabling corroded...

dwalby said:

So given that the ST is an all-aluminum engine I was kinda thinking you had a fighting chance (aluminum heads on iron blocks are more sensitive to overheating because of the dissimilar expansion rates of the two different metals).

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ST1100Y said:

Dunno... friend of mine had an unseen leak in "the valley" on his '96, discovered quite late once the 40A alternator blew its brushes and collector to pieces due the coolant seeping over it.
(Living and working in proximity of the m/way, the temp gauge never got a chance to alarm him about the issue of low coolant...)
So alternator and internal passages (including the elbows) got fixed, but guess what: like 3~4 weeks after the repairs he noticed coolant boiling out the expansion tank... LHS head gasket blown...
While at it anyway we then replaced both head gaskets and gave the rig a detailed overhaul to be sure having covered it all; no issues since.

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the fighting chance I was referring to was the head cracking, which would add to the parts bill substantially, and just having to replace the head gasket isn't pleasant either. Let's hope for the best.

dwalby said:

In a good system it should come on just past 12 o'clock on the temp gauge, but if it takes up until about 3/4 of the way to H don't be surprised depending on the condition of your cooling system.

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I'm hoping my system is in good condition after all the work that's been done.

ST1100Y said:

3~4 weeks after the repairs he noticed coolant boiling out the expansion tank... LHS head gasket blown...

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I agree I'm not "out of the woods" yet; time will tell. I'm hoping I'll be okay since presumably the duration of my incident was much shorter than your friends. During that time (ten or so miles), I shut the engine off whenever the bike was not moving, but left the key on so that the fan would still kick on. So far there's no indication of coolant being lost.

At this point I think I'll put on the upper fairing (so I have lights etc.) and take it on a few somewhat longer rides and see how everything looks.

dwalby said:

...having to replace the head gasket isn't pleasant either. Let's hope for the best.

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Its a serious day's work for 2 persons and one must have a shim-kit avail as it does require complete valve setting as well...

RobbieAG said:

...presumably the duration of my incident was much shorter than your friends.

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I agree, he might have continued commuting with low coolant level for a couple of weeks before the alternator gave in...

Yesterday I installed the upper fairing and mirrors and took the bike for a 17 mile ride. Temp gauge was between 1/4 and 1/3 the whole time. When I got it home, I let it sit in the driveway running for a while and the fan kicked on a little over half. I checked the coolant this morning and no loss. I think I'll take it for one more somewhat longer ride, then if all is good, put the plastic back on and call it done.

glad to hear its all back and running normally, good job.

Congratulations!

jspringator said:

Congratulations!

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Good to hear you dodged the 'bullet'!