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Water Pump Problem????

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Zimmycobra

Zimmycobra

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Have started to run my rebuilt 4A engine on a more regular basis. No trips yet, so very few hours on the engine. Maybe 2 hours total of in driveway running, idling and 1 maybe mile trip. It has been cooling fine until this week.

Engine has new Moss pump with old housing. Wizard aluminum radiator. Electric thermostatically controlled fan (on at 165 deg, I believe). Until now, engine would heat just past middle of gage and then the fan would come on. It would cool down to around the middle and the fan would kick off, etc.

Recently, it heats to red box on gage and the fan does not come on automatically. Top of radiator is very warm but bottom and bottom hose/pipe are cold. I have replaced thermostat thinking it wasn't opening, but no change. I am now thinking that the water pump is no longer pumping! There are no water leaks, but it doesn't seem to be moving water when I look in the radiator fill hole when running.

Any thoughts or suggestions????? Thanks.
 
Sure sounds to me like you've on the right track. My next step would be to pull the pump. There might be something else blocking the flow, but the pump is the most likely suspect IMO.
 
Before the trouble of R&R water pump, take out the thermostat and run without it. See if the system cools that way.Bob
 
I've replaced a good number of water pumps with no appreciable change in temperature performance, so I'm inclined to look elsewhere--but I'd like to know how you resolve the issue. I'd think a new, modern radiator would give superior results and that with timing and fuel adjustments correct, you'd not be hitting red on the gauge. Something mus be connected wrong in the electrics if your electric fan isn't coming on. That much would seem clear unless your gauge is defective. Is that your only fan? You removed the standard fan?

Seems odd you'd suddenly have a big change in performance.
 
A simple quick way to check if the sender or gauge is the problem is if you can lay your hand on the radiator for a few seconds while the gauge show hot. Water pumps leak when they go bad but still pump.

Marv
 
Once found a water pump impeller had come adrift and was spinning on the shaft, leading to sudden overheating. Long time ago, but I think the impeller made some kind of noise which led to finding the problem. Or if the woodruff key was left off the front of the shaft, the pulley could spin without driving the impeller. Loose fan belt is worth a look too.

Viv
 
vivdownunder said:
Once found a water pump impeller had come adrift and was spinning on the shaft, leading to sudden overheating.
Click to expand...
That's what I was thinking. I'm assuming that the fan thermostat is in the radiator, which would explain why the fan isn't coming on. And the top of the radiator being much warmer than the bottom would also suggest lack of circulation.
 
Thanks to all for the suggestions. I am traveling this week so I can't check things until this weekend. I am fairly sure that it is the pump not circulating. When I changed the thermostat to try that, I found a piece of broken metal (I think it was from the heater control valve that was broken in the head when I got it. Replaced with a new one) in the gallery just before the thermostat. I am now thinking that this or another piece of metal either jammed the impeller or at least maybe caused it to shear off the shaft. I will tear apart the weekend to check and/or replace the pump.

I am definitely not getting circulation. Top of radiator is fairly hot but bottom is cold. Radiator is fairly new aluminum and clear so I think that the thermostat is opening but there is no forced flow therefore only a low flow heat transfer to the top water in the radiator. Fan wiring is fine and the fan switch is in the top of the radiator. All makes sense if there is no flow.
 
You would think it would make some noise if it is just free floating on that shaft
 
Only thing, is maybe it has jammed and is just spinning on the shaft. I'm just not sure and won't know until I can tear it apart. I only hope that it is something that I can see and then fix.
 
Still a bit of a mystery. Water pump seems fine. Impeller is still intact and the woodruff key is still in place. Spins properly in and out of the car. If I start to fill the radiator with the pump out of the car, I get water flowing out of the pump housing showing me that the radiator and the lower hose/pipe are clear and the water path is clear back to the pump housing. Belt is tight.

One possibility still is the thermostat. I originally put in an original design replacement from Moss. That was the one that was in when the system was working for the past year (very limited driveway idling and running). When the system stopped and the flow was determined to be the issue, I replaced it with the inexpensive Stant version. It didn't seem to help. I have since read that the original design is important because when it opens it also restricts the bypass opening increasing the flow to the radiator as required. Without this restriction it implies that overheating will still takes place. Since all of my testing has been not driving, I now am wondering if it may just be the thermostat after all and I do need to replace it with the original design to block the bypass. I am ordering a new one from Moss today.

Any comments or thoughts??
 
The difference in cooling with the bypass blocked or open is very small. I've tried various forms of blocking mine off, and never been able to tell that it made any difference at all. From your description, I really doubt that is the problem.

Besides which, your 4A came new without the blocking sleeve. And the non-sleeved thermostat was a factory-approved replacement for the earlier cars that originally had the sleeve.
 
Take the thermostat out, unhook the top radiator hose. Drain the antifreeze and fill with water from the hose. Put the garden hose into the hose at the thermostat inlet and turn it on. Run the engine and see if you get flow out of the top radiator connection. The reverse it with the garden hose, putting it in the radiator and checking for flow out of thermostat. It should work one way but not the other, as your garden hose pressure will be fighting the water pump. If it works both ways, the pump is messed up.
 
I don't think the bypass thermostat is the key, but your current one may be defective or installed incorrectly. You've checked all that? Do you have no standard fan? I wonder about no standard fan + using just an electric puller? I've heard a preference for: standard fan plus pusher. But check the current thermostat and don't put too much hope on the bypass one-I think that design was for climates where it made sense to have a small amount of coolant bypass the radiator for a reason barely relevant in warmer weather. Just my recollection from the words of some wizards around here.
 
KVH said:
I think that design was for climates where it made sense to have a small amount of coolant bypass the radiator for a reason barely relevant in warmer weather. Just my recollection from the words of some wizards around here.
Click to expand...
Actually, the bypass itself is required in all climates and is a standard feature on virtually all water-cooled engines. It is important to have the water still circulate before the thermostat opens, to ensure even heating of the cast iron cylinder block and head. The circulation also carries hot water to the thermostat bulb, so it accurately senses overall temperature.
Without the bypass, you can potentially get hot spots (especially around the exhaust valves) that will actually boil before the static coolant at the thermostat gets hot. Then when the thermostat does open, it allows cold water from the radiator into the engine and suddenly cools those hot spots. The sudden thermal shock can crack the relatively brittle cast iron castings.

The issue is what happens to the bypass when the engine warms up. For maximum cooling, you want all of the coolant to go through the radiator, and none through the bypass. So some engines, like the earlier TRs and later Stags try to block off the bypass when the thermostat is fully open.

But the difference is small (usually cooling is limited much more by airflow through the radiator than coolant through the radiator) and so most manufacturers just ignore the problem. Triumph switched to the simpler thermostat (which leaves the bypass open all the time) some time during TR4 production.

One option is to block the bypass permanently (I tapped the WP fitting for a pipe plug, but I understand a 1/2" copper pipe cap fits snugly in the hose and works just as well); and drill a hole through the thermostat back plate so some coolant flows all the time. This will slow down the engine warm up to some extent, but that's usually not an issue in warmer climates. Probably not a good idea if you drive in freezing weather though, as it may keep the engine from ever reaching operating temperature.
 
My 4A came with a 160 thermostat with the blocking sleeve. Just replaced it last year after it failed in the open position and I could not get my car up to temperature.
 
Thanks guys. Sounds like the cheaper Stant regular thermostat should work just fine. No need for the $109 one from Moss.

Is there a simple and fairly non-messy way to be sure that there is no blockage in the block water passages? Since all of this system did work correctly and suddenly stopped a few weeks ago, I am wondering if something is blocking the block passages especially after finding the piece of broken metal in the thermostat gallery.
 
What if you open the block drain above the starter and just run a hose continuously. Messy but what choice? You need to know the passages are clear. Seems you need to rule out foreign objects in the system though that would be odd. If it were me I'd also have that radiator out if there and check the hoses and flow with water from a garden hose.Nothing should have "broken off" in there. How long do you idle before the engine overheats?

By the way, I'd probably remove the thermostat housing and check the passages first if you really think pieces of metal are inside the hoses or head. You need to know how that happened and avoid lodging anything deeper into the galleys.
 
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