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Tiger Time => Steamers (1993-1998 Tigers) => Topic started by: 97tiger885 on March 13, 2014, 03:27:49 AM

Title: Thermostat or Water Pump
Post by: 97tiger885 on March 13, 2014, 03:27:49 AM
The 97 has been having cooling problems since October.   The gauge isnt spiking into the red but is moving oddly. For example,  it will be at the normal temp mark, suddenly drop to the bottom line for minute, then jump back to the normal temp mark.  It is not a gradual increase and decrease.  The fan is working.

The mc is definitely overheating.  This isnt an issue at 40 degrees but it is at 60, esp in stop and go traffic.

Is this more likely to be a water pump issue or a thermostat issue?

I have the Trident ready for head removal, so I can replace the Tiger thermostat with the Trident thermostat. 

I also have a used pump that I can put on the Tiger.  Is the pump fix swap-and-go or will I need to replace gaskets, o-rings and such?

Which should I do first?  Or should I do both?   I need to drain the coolant for both jobs, right?

Title: Re: Thermostat or Water Pump
Post by: dave NL on March 13, 2014, 08:35:33 AM
When overheating, is the coolant resevoir bubbling? Then the head gasket is leaking, this also causes the temp gauge to be erratic. It does not have to be in the red with a starting to leak head gasket, dont ask how i know....

During warm up fase the thermostate does its job, when warm it stays open. Usually when a thermostate brakes down or the function decreases it will stay open, so warm up fase takes a long time or does not warm up at all at low temperatures.

You can check the pump for piece of mind, check the axle and impellor that there fixated and run freely, it is a bullitproof thing imo. Only the bearings can go really.

A head gasket replacement is not the end of the world anyway, might this be the case,,,,,, :icon_confused:

You will need a O-ring kit for the water pump, especially for the pump casing halves, this o-ring will harden over time.
Title: Re: Thermostat or Water Pump
Post by: rybes on March 13, 2014, 09:20:28 AM
i think its the temp sender that causes that. mine done it for a while till i stopped workin completly. the water pumps fine so it mustve been that. really wish i sorted it sooner cos it would saved me gettin a new engine from cookin mine  :icon_cry:
Title: Re: Thermostat or Water Pump
Post by: dave NL on March 13, 2014, 11:59:36 AM
Yes, but a broken sender does not cause overheating....
Title: Re: Thermostat or Water Pump
Post by: Sin_Tiger on March 13, 2014, 01:19:15 PM
Just remember that the gauge temp sensor and fan controller are separate on Steamers.
Title: Re: Thermostat or Water Pump
Post by: Bixxer Bob on March 13, 2014, 01:38:53 PM
Quote from: Sin_Tiger on March 13, 2014, 01:19:15 PM
Just remember that the gauge temp sensor and fan controller are separate on Steamers.

That was helpful Sin.  So it looks like intermittent wiring fault on the gauge / loom / gauge sender  somewhere and a non-working sensor for the fan.  I don't have diagrams for a Steamer so I guess Mustang will jump in with the diagnosis tests.
Title: Re: Thermostat or Water Pump
Post by: rybes on March 13, 2014, 04:14:11 PM
Quote from: dave NL on March 13, 2014, 11:59:36 AM
Yes, but a broken sender does not cause overheating....

very true but it wouldve alerted me to the fact i had a lack of water  :icon_redface:
Title: Re: Thermostat or Water Pump
Post by: 97tiger885 on March 13, 2014, 06:51:49 PM
Quote from: dave NL on March 13, 2014, 08:35:33 AM
When overheating, is the coolant resevoir bubbling? Then the head gasket is leaking, this also causes the temp gauge to be erratic. It does not have to be in the red with a starting to leak head gasket, dont ask how i know....

Ok, so to test for a head gasket leak, I can let the mc idle until the gauge spikes and see if the reserve coolant is bubbling?

QuoteDuring warm up fase the thermostate does its job, when warm it stays open. Usually when a thermostate brakes down or the function decreases it will stay open, so warm up fase takes a long time or does not warm up at all at low temperatures.

I am hoping the thermostat is sticking and unsticking.  Temp spike up as it sticks; temp spike down when it opens.

Not warming up at low temps doesnt help with diagnosis since the Tigers dont warm up in cold weather.  Isnt that what the winter shielding of the radiator was all about?

QuoteA head gasket replacement is not the end of the world anyway, might this be the case,,,,,, :icon_confused:

End of world, no.  End of Tiger for me, maybe.   We will see how the Trident head gasket goes.  The Tiger needs some serious rehab at this point:  chain and sprockets, clutch, voltage regulator, valve adjustment.   I was hoping to nurse it along for another 5000 miles.

QuoteYou will need a O-ring kit for the water pump, especially for the pump casing halves, this o-ring will harden over time.

I will need to order that before I do any swapping.

First I will check for a head gasket leak.


Thanks for the help. :icon_cool:
Title: Re: Thermostat or Water Pump
Post by: Bixxer Bob on March 13, 2014, 07:32:21 PM
Quote from: 97tiger885 on March 13, 2014, 03:27:49 AM

Which should I do first?


The easy stuff.  Guage is likely a wiring fault, check and sort it.

Overheating:  take the thermostat out and put it in water. Bring the water to the boil and it should open. If it does, it's ok, if not replace it. 
Title: Re: Thermostat or Water Pump
Post by: ssevy on March 14, 2014, 03:26:06 AM
You can also jump the fan wires to see if the fan is working. If your bike runs cool and the fan rarely comes on, the bearings can seize. Lots of used fans if you need one; just be sure the rotation is correct as some are push and some are pull.
Title: Re: Thermostat or Water Pump
Post by: dave NL on March 14, 2014, 08:10:10 AM
For the head gasket check...

-first check if the coolant is topped up!  :icon_wink:

- Then drive it like you stole it to heat it up, then stop alongside the road and take off the seat, when there are bubbles going in to the cooling water reservoir, 80% change of a BHG. (Do check the hose from the radiator to the reservoir)
Title: Re: Thermostat or Water Pump
Post by: Sin_Tiger on March 14, 2014, 12:15:04 PM
When you get the more complex cooling issues a really useful tool for diagnosing the root cause is an infrared non contact thermometer. They're inexpensive these days.
Title: Re: Thermostat or Water Pump
Post by: Bixxer Bob on March 14, 2014, 01:09:25 PM
Yup,  I bought one for about £10 when I was trying to work out which wheel bearing was making a bit of noise on my 4 x 4.
Title: Re: Thermostat or Water Pump
Post by: 97tiger885 on March 15, 2014, 02:35:42 AM
I have coolant in the radiator and the expansion tank.

The fan is fine.  The temp sensor is turning it on.

I put the Trident thermostat in the Tiger.  The Tiger thermostat opened in boiling water.

I let the mc idle until the gauge hit 2/3.  No bubbles.

Tomorrow I will run the mc hard , see if the thermostat switch makes a difference, and get it hot to check for bubbles.


dave NL:  I always thought it better to be a smart criminal.  That means no identifying tatoos and obeying traffic laws in stolen vehicles.  Dont make it  easy for the cops to catch you.   But I get your point.
Title: Re: Thermostat or Water Pump
Post by: ssevy on March 15, 2014, 03:34:38 AM
How is the condition of your coolant? If it is rusty you may have a partially plugged radiator, which would allow for some cooling except under high heat/load. I haven't seen this on my bikes, as I flush and change the coolant when needed and run good stuff in them, but I have had this happen to me with cars. It is also easy to get an air pocket in these when refilling, and this prevents coolant from circulating properly. Last idea is the heater hoses. They do age, and perhaps one is partially collapsed where it is difficult to see, and again, passes enough flow under light load, but not under heavy? I know when I swapped out a new starter on my buddy's Legend, the routing of the coolant hoses near the starter made it easy to partially compress them if not careful when reinstalling the new starter.
Title: Re: Thermostat or Water Pump
Post by: Bixxer Bob on March 15, 2014, 07:59:20 PM
These engines are aluminium alloy Sevvy, the radiator too. Not sure why you'd get rust in there although I follow your logic for old cast iron engines in cars, trucks etc.
Title: Re: Thermostat or Water Pump
Post by: ssevy on March 16, 2014, 12:07:43 AM
Hmmm..my overflow tank had brown rusty fluid in it when I bought it. Must be from some other cause? Well, take thatone off the list of possibilities I guess :icon_redface:
Title: Re: Thermostat or Water Pump
Post by: Mustang on March 16, 2014, 12:14:45 AM
shhhhh .....the liners are steel and guess what they sit in ?  :nod
Title: Re: Thermostat or Water Pump
Post by: 97tiger885 on March 16, 2014, 03:54:11 AM
Took a trial ride today.  The gauge behaved itself quite nicely.  Looks like  the Tiger thermostat was worn out.  Wont know about the overheating in stop and go traffic until temps go back up.
Title: Re: Thermostat or Water Pump
Post by: Bixxer Bob on March 16, 2014, 10:47:08 AM
Quote from: Mustang on March 16, 2014, 12:14:45 AM
shhhhh .....the liners are steel and guess what they sit in ?  :nod

Doh!     :BangHead

Sometimes you can overlook the obvious if you overthink it.  That's why I'm always saying, simple stuff first.
Title: Re: Thermostat or Water Pump
Post by: Sin_Tiger on March 16, 2014, 11:29:48 AM
Quote from: Mustang on March 16, 2014, 12:14:45 AM
shhhhh .....the liners are steel and guess what they sit in ?  :nod

:bad had several Rover V8s (derived from a small block Buick) although it was all alloy they used to suffer from build up of sludge in the bottom of the radiator. This was exacerbated by the engine being a big lazy lump rarely got stretched meaning the engine driven water pump wasn't running at optimal speed and many cooked engines ensued blamed on a whole menu of issues designed to swell the bank accounts of many workshops.

End of the day,  regular flushing and use of a good quality additive to maintain the nitrate levels is the best option,  just make sure you choose one that has alloy inhibitors built into to the additives.
Title: Re: Thermostat or Water Pump
Post by: 97tiger885 on March 16, 2014, 05:06:30 PM
Rode to breakfast, 25 miles each way, in high 20s F.  Tiger warmed up faster than it has been doing recently.  Definitely had a thermostat problem.

QuoteBixxer Bob
That's why I'm always saying, simple stuff first.

You want simple?  I didn't realize the Tiger had a thermostat until I took the radiator off the Trident and saw that the Trident had one.  That is simple.
Title: Re: Thermostat or Water Pump
Post by: Sin_Tiger on March 16, 2014, 10:48:01 PM
That's good to hear, far better than another "head off" thread  :XXsunsmile
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