Running Too Warm

[Dan Sarandrea (Phila)]

Running Too Warm----Results Added 11/4/13

Oh Noooooo, not another running too warm/hot thread!:fart::nod:

During final prep I tested the cooling system with a pressure tester, and I had to replace the original-to-the-car water pump because it was leaking, probably due to sitting for close to six years. I ordered the pump from one of our regular vendors, but like a dope, I forgot to pay close attention to the impeller to body clearance and installed it without checking.

Have taken my car out about seven times since it got back on the road. The car operates at normal temps (190-200°) at cruise, but when idling or in slow traffic, temps gradually creep up to 225-230°, but will come down once moving at cruise again.

After eliminating other causes for this behavior (bleeding, thermostat, etc), as much as I did not want to, I had to remove the pump and check the clearance.

As I was removing the alt and the access panel in order to get to the pump, I noticed a "leak trail" from the pump body. The trail lead to the plug installed in the pump body that blocks off an unused heater return tap. The sealant used was not cured properly, allowing the very slow leak.

Once the pump was removed from the car, I checked the clearance as best I could and from what I could tell, it was between .050 and .055, which is too much!!!

For comparison, I checked the clearance on the OEM pump that I removed because it was leaking, and that seemed to be in the mid-.030s range.

I disassembled both the old and new pumps (removed the impeller and pulley assembly from the pump body) and started mixing and matching to see what combination of pump body, impeller/pulley, and gasket gets me the tightest fit.

My proposed course of action is to use the original pump housing with the new impeller/pulley assy. I plan to take it to my buddy who owns a machine shop, where I can bead blast the pump body to remove the internal scale, and then ask him to mill the right amount of material off the face of the pump body to get the clearance to the tight end of the spec range.

Will post pix tomorrow nite.

 

[budgetzagato]

Did the radiator fan(s) come on?

 

[Dan Sarandrea (Phila)]

I have two, one controlled by the normal rad fan switch on the left side of the rad, and the other controlled by an aftermarket controller whose sensor is placed next to the right side rad inlet nipple.

They come on independent of each other.

They don't come on much while driving, but after an extended idling period last Sunday just to see what their behavior is, they do come on normally.

I think this is a classic "not enough flow at low speeds" situation.

 

[TonyK]

Impellar Clearance

This should be at the min. to have good circulation at Idle.

The reason that the fan does not come on is because the hot coolant is not getting to the rad. or you have air in the system.

TonyK

From Radcliff Kentucky

 

[Dan Sarandrea (Phila)]

Tony, my machinist buddy can make the clearance anything we want, do you think there would be any harm or benefit to closing it up to tighter than spec?

Coming from the "If some is good, more must be better" school of thought:fart:, I'm sorely tempted to get it as close as possible under the (good or bad) assumption that the closer the clearance the better the flow at slow RPMs.

 

[lookforjoe]

Dan, are you shooting for .030" impeller clearance, or tighter?

 

[Dan Sarandrea (Phila)]

Unless someone can rationally explain why not, I have to think that the tighter the clearance the better the flow is going to be. Of course when arriving at the magic number it would be wise to take thermal expansion of the pump housing into account.

The downside is that the more you mill off the face of the pump body the more off-line your pulley is going to be in relation to the other belt-drive accessories, but I can't believe .050 one way or the other is going to create a problem.

 

[lookforjoe]

No, I'm not concerned about belt alignment - that is not enough to matter. I going to have the cast housing milled - the housing is so meaty I wouldn't expect to see any significant expansion concerns. I'm going to shoot for .025-30" max. That will effectively half the current clearance.

 

[budgetzagato]

A Stupid question...

Can the impeller be removed and reinstalled to correct this? It's pressed on isn't it?

 

[ng_randolph]

Can the impeller be removed and reinstalled to correct this? It's pressed on isn't it?

Yes the impeller is pressed on. I used a puller to pull the impeller off the shaft just enough that my pump clearance is now at the low end of the spec.

I believe the concern with too little clearance is cavitation at high RPM, so I stayed just at the spec limit.

 

[lookforjoe]

That's a good alternative - to machining the housing...

 

[jvandyke]

I'll confess to much ignorance on this (I wish I had checked my new pump before I put it in)
But wouldn't repositioning the impeller just increase the clearance on the other side so it may be better but not as good milling the housing?

 

[fiatfactory]

My day job (these days) is building and maintaining BIG pumps for underground mining. I can assure you tight clearance is vital for efficient pumping. In large centrifugal pumps, the neck ring clearance is about 0.2mm, if this wears to approx 0.4mm pumping efficiency drops by about 30%... the impeller pumps on our little engines aren't quite the same, but a close fit is a good thing, as little as 0.5mm is works well, just enough so nothing touches.

It's not going to fix a blocked radiator or other issues, but you might as well have it pumping as efficiently as possible.

SteveC

 

[ng_randolph]

There really is no "clearance" at the back side of the impeller, so moving the impeller on the shaft has no ill effect. From the back side of the impeller there is on the order of an inch distance to the bearing carrier. See photo (links to Midwest Bayless):

 

[Dan Sarandrea (Phila)]

Hi Bjorn,

I do remember a previous post in which you stated that you used a puller to move the pressed-on impeller on the shaft (drawing the impeller away from the pump pulley end of the shaft) to tighten up the clearance.

Did you do this with parts at room temperature or heated up to mimic engine operating temperature? I am not familiar with how all the pieces of the pump go together. Is it designed in such a way so that repositioning the impeller on the shaft will have no effect on the effectiveness of the shaft seal or the positioning of the shaft bearings and the shaft end play?

 

[ng_randolph]

I did this at room temperature. The FSM states 0.8 mm - 1.3 mm clearance, and I figured this would be cold (after all, by the time you get far enough into things to measure the clearance, the engine would be cold).

The only thing that moves in the process is the impeller with respect to the shaft. Seals and bearings are not disturbed at all, i.e. the shaft does not move with respect to the seal or the bearings.

 

[lookforjoe]

My 'new' pump from Bayless has a plastic impeller. I never checked it when I purchased it

So, I either shave the housing, or buy another pump (without the housing?) no way to safely pull the plastic impeller.

 

[Dan Sarandrea (Phila)]

Water Pump Pix

Original water pump, body and impeller halves. Some of that white powdery cooling system plaque but not that much. Pump was replaced because the seal leaked.

New pump impeller after removed from new pump body.

Original pump body after bead blasting.

Master plan: Fit new impeller assy to original pump body. I was originally going to machine the pump body-to-impeller mating surface, but Bjorn (member name ngrandolph) posted that you can use a good puller to pull the cast iron impeller on its shaft and reposition it for tighter clearance, which is what I did.

Here's the impeller clearance with original pump body, gasket, and new impeller fitted and secured with bolts....the .040 wire feeler gage was pretty loose, so I'd guess at least .050.

Final fit: the .015 wire feeler gage could pass on some vanes but not others.

The rough casting of the impeller vanes probably accounts for why the factory specced .030 as the minimum clearance, it was probably the smallest gap they could spec that allowed for the wide variability in the vanes of the cast iron impeller.

This pic shows the hand filing that I did on two vanes that were appreciably longer than the rest. These two rubbed the pump body so I filed them down. It took about six file-test fit-file-test fit cycles to dial it in.

Be sure to install the gasket and tighten down all four impeller to pump body capscrews and hand spin the belt pulley before declaring victory.

 

[lookforjoe]

Nice work!

I took my original pump apart this evening. The bayless pump has the plastic impeller - the blades are shorter

Pretty sure the stock deeper blades will do a better job of pushing the coolant.

I also found the variation in vane height to be an issue - so I had to clean up the inner edges also. Mine is now approx .016" clearance

I didn't use a puller though - just set the impeller on two blocks of wood over a vice - then whack the pump shaft with a hefty punch to decrease clearance.

 

[jvandyke]

:thumbsup:BIG HAMMER FIX :thumbsup:
:hammer::hammer::hammer: