to much water flow?

[willibig]

I have now had my Peninsular 300 hp engine now for about two and a half years and since i got it i had problems with overheating. I spoke with Peninsular a few times about the problem and they gave me some expensive ideas that "might fix" the problem but i had all new cooling components such as dual thermastat setup high flow water pump 6 row radiator... and non of these have helped much with temps with no load getting above 220+ easily doing 70 mph on flat roads and even higher when going up hills, towing is just about out of the question which is sad because that is one reason i decided to get the engine in the first place. Any way i have had some people say that I could be flowing to much water through the radiator not giving it the time to cool, does this have any validity.

Thanks

[NH2112]

That sounds exactly like the problem you have. During my time in the south I knew more than a few good ol' boys who swore you didn't need a thermostat down there because of how hot it was, and who inevitably kept overheating on the trails. No thermostat and very low-speed driving are a great combo for overheating. As far as what it would take to stop the overheating, I'd say you need some kind of restriction to coolant flow to let it stay in the radiator longer. Perhaps changing the thermostats for ones that open at a lower temp would work.

[CareyWeber]

willibig,

What thermostat are you running?

If you are running 180

[jcomp]

Are you still using the mechanical fan? How's the clutch? Are the thermostats installed correctly? Is the lower radiator hose collapsing?

If you think you have too much water flow, you could try replacing a thermostat with a metal disk or making one nonfunctional and see what happens.

FWIW, I've got a penninsular dual t-stat kit on my truck and I've yet to see coolant temps above 195 degrees, even during extended runs with 800-1000 degree EGTs.

If everything is functional (fan clutch, thermostats, etc.) and you're still overheating, I would look into finding ways to get more airflow across that big radiator. Maybe try removing a fenderwell and whatever is in front of the radiator or installing an electric pusher fan.

I had similar symptoms on a toyota with a chevy 350. The problem turned out to be that the air was being trapped in the engine compartment.

[willibig]

I have tried all three thermastats (160, 180,195) and right now i have a combo of 160 and 195. I'am using the machanical fan and clutch that was replaced at the time of the engine swap and three more times after that, all of which show no signs of engaging till 230 or better. I have tried pusher fans puller fans, i created an air dam to help create a low pressure area in the engine compartment i took out the rubber splash guards on the fenders, i moved my engine oil coolers to under the drivers door, and put high flow trans coolers in front of the radiator and that is it except for the AC condensor. the thing that bothers me is that i have most of my problems happen when at 65 plus even with no ac on flat roads. i think i will try blocking off one of the thermastat passes and see what that does. Let me know if there are any more ideas.

by the way i don't remember if i said this in the first post but my EGT's post turbo never get above 600-650 unless i change altatude (3500+ feet).

thanks

[whatnot]

Have you verified that your gauge is correct?

[willibig]

I'am running two guages one stock and one aftermarket autometer. I have also used 3 different guages to be sure.

Thnanks.

[crew84]

Your problems remind me of two different things that can go wrong. One is the water pump impeller that was pressed on wrong or the wrong one for the application. The other is the gasket that mounts the water pump is partially blocking the engine water block ports. Either one can cause your symptoms. I would also put a radiator/ cooling system pressure tester on it and pressurize the system for a while. Look for a very slow pressure loss. Sometimes a slight crack/head-gasket leak when hot will do the same overheating. Good luck!

[willibig]

I have had the problem since the engine was new so i don't think that it is a cracked head and the hose does not colapse. I think i will look into checking the pressure that sounds like a good idea and maybe sometime in the near future i will take off the water pump and check that eh impeller is correct and the ports are not clogged. good ideas guys, keep them coming.

[CleviteKid]

Your fan clutch not engaging until the coolant hits 230F seems like a problem. Contact Kennedy to see if he has one of his fan clutches that will fit your application.

Try running without the hood. This will tell you if you are trapping hot air in the engine compartment ! ! !

Dr. Lee :cool:

[gmctd]

Two distinct waterpumps are available for the 6.2\6.5l engines - clockwise rotation for the v-belt drives, and counter-clockwise for the serpentine.

On the cw version, the passenger-side outlet comes from the bottom and behind the inet passage, the driver's-side outlet comes from the top.
This pump has a 3/4" bypass connection.
Part number on this pump is 5008-11

On the ccw version, the pass-side outlet comes across from the top, the driver-side comes off the bottom.
The bypass outlet is 1".
Don't know this part number, but it is not 5008-11 - may have HD cast into the driver-side upper.

Fan clutch is also specific, and usually is imprinted CW or CCW.

Fan is also specific - cw blades curve engine to radiator to the driver-side, ccw blades curve engine to radiator to pass-side.

[willibig]

I would love to get a clutch that engages at lower temps but all the clutches i've had are about the same two of which have been GM parts, as for kennedy i called him a year ago and at that time he did not have them, i will try again on monday. gmctd thanks for the info on the water pumps ill put that to use in a min. The clutch is correct and the fan are also correct. I think that i will also try taking off the hood to see what happens.

Dr. Lee what do you think about getting to much water flow? is this a valid idea, i read some from water manufactures and they say that you can never have to much.

thanks

[CleviteKid]

You can NOT have "too much" water flow, but you CAN have "too little" air flow.

The air flowing thru your radiator will take out as much heat as it can. The hotter the water, and the bigger the temperature difference, the more heat the air can take out.

If you have the wrong water pump, as gmctd indicates, you will have too LITTLE water flow, and the water in the block will overheat. If you have the wrong fan blade, you will have too LITTLE air flow, and will not take enough heat out of the water. At 65 mph, with the hood off, level ground, not towing a load, you will have plenty of air flow through the radiator. If it still overheats in this configuration, you have too little water flow to and through the radiator.

If you have a theromcouple you can put on the radiator, you can compare radiator coolant temp to block coolant temp. If the radiator is cool, you are not flowing enough water. If the radiator is as hot as the block (almost) then you are not flowing enough air through it. Don't take the pressure cap off to measure radiator coolant temp; at 230 F in the block you will make steam and really overheat your engine.

Dr. Lee :cool:

[Dieselboy]

As for the fan clutch not engaging at a low enough temperature, I found that heathdiesel.com (a DP advertiser) sells cw rotation Hayden severe duty fan clutches for the 6.2L crowd.

While there has been some dispute in the 6.5L forum that the hayden clutch in nothing more than a re-badged factory clutch, I have to say that mine does engage at ~210*F and brings the temps right back down. That's something my factory clutch wouldn't do.

I think it was around $80 shipped.

[willibig]

Took the truck out today after removing the hood to check if i have a low pressure area in the engine bay and it seems as though i don't. I made a run keeping the truck at about 75 mph on the highway that only has small hills and after about 10 minutes the temps increased to 230 with A/C on. The EGT's never got above 700 the boost stayed around 4 PSI unless going up one of the small hills. I saw no effects of the fan clutch engaging, but at 75 mph i'am not sure that it would do much good anyway. As soon as i got off the highway and resumed speeds closer to 40-55 mph the temps droped back down to where i like them which is around 190 with the A/C on. This leads me to believe from Dr. Lee said that my problem is not air flow but most likely a water flow issue. With this knowledge i looked at gmctd's post about how to tell the water pumps apart and i was not able to understand what i was looking for except for the bypass size which is the 3/4 inch. I will look for the part numbers in the next few days to be sure that it is the correct one and possibly replace as well just to be sure. This brings up another question: Which v-belt pump should i get and where should i get it from?

Thanks

[NH2112]

From what gmctd wrote, it sounds like you need the ccw water pump if you have a serpentine belt setup, and the cw pump if you're running a V-belt. I'm assuming your engine runs a serpentine belt, and if so you should have the water pump with 1" bypass hose.

I had a Dodge a while back that would run hotter than it should at highway speeds, and cool right down in town. After replacing the pump it ran at normal temps on the highway, which led me to believe it was cavitating at high RPM and thus not sending a steadyflow of water through the radiator. I also have a friend whose Jeep Wrangler used to overheat badly, till she realized it had a fan for a V-belt water pump on it.

I think Dr. Lee is technically right about being unable to have too much water flowing through a radiator, but that if the water flows through so fast that the available airflow isn't able to remove enough heat, it's a water flow problem and not an airflow problem. If you're not getting enough air at 75mph, you can't really increase speed to get more! I liken it to hot water coming out of a faucet - if you hold your hand in it you get burned, but if you rapidly flick your fingers through you don't even feel the heat. It sounds to me like you need to do something to slow the water down as it's passing through your radiator, to allow it to shed more heat.

Also, I think you should be seeing higher EGT than what you are. Indirect-injected engines are less efficient and retain much more combustion heat than direct-injected engines, and anything not going out the exhaust is basically being removed by the coolant.

What's your coolant concentration, BTW?

[gmctd]

The Pen hi-flow pump is casting # 5008-11, with a 'capital A in a circle' brand, cast into the intake housing.
It has a 4"dia impeller in a 6.2L casting - the inlet is small, not machined.

If you check around, you'll find the same brand, casting # 5008-11-1 as 6.2L replacement cw pump.
It has the fully machined, id and od, large diameter inlet, same as the 6.5L pumps, and flows more than the stock GM 6.2L pump.
It has the 3.875" impeller in a 6.5L-equiv casting.

Would have been more efficient if Pen had spec'ed the -1 housing for their hi-flow, as the 6.2L inlet size restricts flow somewhat.

Also, on the hi-flow, I had to remove 1/4" of cast iron from the driver-side casting to match that outlet to the backing-plate diameter.

The outlets in the -1 casting matched the ports in the plate.

On either pump, I also counter-drilled and tapped the bypass outlet to 1", to further match the 6.5 flow dynamics.

Needless to say, I am very disappointed with the hi-flow pump.

I'm thinking on buying another hi-flow, breaking it down to install the parts in the -1 casting, re-machined slightly to accept the larger impeller.
Can be done with a die-grinder and a sure hand, but a mill is the ticket.

Ain't no hill for a stepper......

p.s. NAPA carries the -1 at 65 bucks


edited for content, and to run in the alloted time, and to fit your screen width tongue.gif

[ 06-28-2004, 05:50 AM: Message edited by: gmctd ]

[willibig]

My coolent mix is around 70/30 with two bottles of "Water Wetter". I have tried many mixes such as 50/50, 85/15.

My truck is using the old V-belt setup that came on the truck in 1989 still.

"gmctd" if i use the -1 pump without modifications do you know what flow it runs? If i'am correct what i should have from Peninsular or what i asked for them to install on the engine before it left their shop is a 110 gph pump. What i'am affraid of is that they forgot to do this and left the pump that came on the engine from AM General where they claim to have gotten the engine, which would be the 106 gph counterclockwise pump.

Thanks

[gmctd]

Turbo'ed 6.5's have had the 1" bypass since at least '94, so that 3/4" pretty much points to the cw pump.
'98 up ccw pumps have the 'HD' casting mark.

Don't know actual flow rate of the -1, but the increased inlet diameter would indicate somewhat better than the factory version.

The 5008-11(x) casting # is on front side of the inlet casting, between the radiator hose and the drive pulley, fairly easy to see.

For the price of the pump-to-timing cover gasket and some time, you can verify the driver-side outlet mismatch, if any exists.

I'm fairly certain this restriction would result in increased flow into the passenger-side bank, causing heating problems in the driver-side bank.

Also, imo, the bypass should be up-sized to the 1" 6.5 configuration.

A 20" 7-blade cw fan, of GM manufacture and hub dimension, is available from Chrysler.

[ 07-06-2004, 06:18 PM: Message edited by: gmctd ]

[gmctd]

Further note, here -

Just returned from a 300mi trip with the new hi-flow waterpump, new 'green' coolant - temps ran 20deg higher at 60mph than at 70mph with 5008-11-1 pump.
Really started climbing between 65-70mph.
A\c added 10deg to base condition.

Something very strange going on - switching back to a new -1 pump fromn NAPA, make the same trip next couple weeks for determination.

I am puzzled, and perturbed, having solved the 6.5L TD\old-body-style-vehicle overheating problems back in ought one.

Guess I oughtta touch on that a bit -

Factory 6.2L config had the auto trans cooler in the radiator hot tank - that was bypassed to external only, tube-and-fin.

Factory had eng oil cooler in radiator cool tank - that got external cooler first in line from engine, then to cool tank, back to engine.
Regulates oil temps in winter, helps cool-tank cooling in summer.

Opened 5008-11-1 bypass to 1", same as 6.5L.

With this configuration, coolant temps were seldom above 210deg, towing thru Texas Hill Country with a-c on in July, ambient ~100deg.

Would idle for extended periods with a-c on, coolant below 200deg - with factory 6.2L 5-blade 20in fan, HD clutch

Also, ECT coolant temps in t-stat crossover are now higher than instrument panel gage, from probe in cyl head.

Before hi-flow wp, gage\head temps read 10deg higher than ECT readings on Tech-II.

Puzzling, indeed....

[ 07-03-2004, 04:29 PM: Message edited by: gmctd ]

[willibig]

Before i bet another water pump, is there a way to check flow through the radiator to see if it is flowing up to speed.

Thanks

[gmctd]

Crank it up cold, turn on a-c at idle, watch coolant agitation in filler neck (cap off, of course).
Should be some, as t-stats are closed when coolant is coming off ambient, but heater bypass return is in cool tank.
Rev it a little, should show some surge.

Watch as temps come up to normal t-stat range - should be more flow agitation, particularly when revved some.

Other than that, I don't know - I installed a brass ball valve in the heater bypass for some r&d.
Did not seem to make any difference this trip - temps are running higher, 70 mile jaunt, or to and from work.

I should have more info, later this week.

[gmctd]

Update -

I've dissected three water pumps
1 GM 6.2 cw
1 GM 6.5 ccw
1 am 6.2 cw

All three pumps appear to be of same manufacture.

The aftermarket 6.2 cw pump is on the same frame as the GM 6.5 ccw pump, with 1.75" machined inlet diameter. Od is also machined.
6.2 pump has 3/4" bypass (1/2"npt), 6.5 pump has 1" bypass (3/4"npt).
Both have aux 3/4" port (1\2"npt).

GM 6.2 cw pump has 1.625" inlet, unmachined id or od, 3/4" bypass.

All three pumps have 3.875" impeller diameter.

GM 6.5 and 6.2 am impellers are mirror image, thicker than oem 6.2 pump.

In impeller intake area, bearing\seal casting diameter, at 2.1875" is same on all three pumps, which is intake orifice inner diameter.
Intake orifice outer diameter, at 2.750", is also same.

Preliminary inspection indicates hi-flow pump is of same manufacture, on 6.2 small frame with unmachined 1.625" id inlet, 3/4" bypass, 4" impeller diameter.

The hi-flow is still on the truck, undergoing further testing, but will dissect it when 6.2 waterpump back plate can be acquired.
That cw pump plate is becoming scarce as hen's teeth.

As the hi-flow pump appears to work well in lower rpm ranges, below 2000rpm, focus will be on impeller intake area and pump inlet diameter for possible cavitation.

Transferring the hi-flow parts from the small 6.2 cw frame to the large 6.5 cw frame casting will be one test.

More, later.....

[ 07-16-2004, 03:02 AM: Message edited by: gmctd ]

[whatnot]

cw and ccw backing plates are different? :eek: I guess I got lucky when I put the engine in my 93. I think I just used the one with the best paint.
I will see if the old one is still laying around here.

[gmctd]

Difference would be in V-belt drive or serpentine belt drive.
I retained the v- drive - ~50% less clutter behind the fan - transferring it to the '95 6.5TD.

[gmctd]

Here's the deep skinny on the hi-flow cw water pump, for v-belt drives.
I had planned to do some further testing, but I just can't stand not knowing -

First, let me say that this is the only one I've seen, and so may be a 'Monday morning\Friday afternoon' version.

But, it is defective in casting and manufacture.

Again, the drivers-side 'channel' did not match the gasket and backing plate orifice by ~0.250", required extensive grinding out with a carbide burr.

The shaft bearing\seal casting area is offset to the drivers side with respect to the impeller area.
When the bearing casting is bored in alignment with the impeller area, the remaining offset stock reduces the impeller intake orifice from 0.300" to 0.250".

Impeller inlet orifice is uniformly 0.300" in the other pumps - one GM ccw 6.5, one GM cw 6.2, and one aftermarket cw 6.5\6.2 version.

Impeller blades rotate in a machined concave area , extending from the outer orifice edge, and varying between 0.525 - 0.530" in width

That area is 0.650" width in the other pumps, closely matching impeller blade length.

Hi-flow pump has longer impeller blades, to make the 0.125" increase in diameter from 3.875" in the standard pumps.
0.530" does not come close to area required for longer blades.

The od of that machined area drops off into the channels that direct flow to the left and right banks.
This results in a large area of hi-flow impeller blade rotation in 'un-dedicated' area, with possibility of turbulence and back-flow.

Reduction of impeller inlet orifice area creates probability of cavitation at higher rpm, particularly when combined with increased length of impeller blades, designed for higher flow capability.

Pump inlet id, intake from radiator, varies between 1.625" and 1.750", where 6.5-frame pump is machined to consistent 1.750" id.

The bearing seal casting is 2.175" dia; the mating separator ring on the impeller is 2.205" dia, providing some further reduction in impeller inlet area, and possible cause of turbulence.

And, while this probably has no bearing (snicker!) on the subject matter, the shaft\bearing assy is of Chekoslovakian manufacture, with date code of 26-02-04.

Which means I did not get an old reject, laying around on some back shelf for a few years.

So, this am, I installed a new NAPA 5008-11-1 pump - no cooling problems with that one.

Still doing some mixing and matching with the other pieces.

And, I do need to dissect a GM HD 130gpm pump for serpentine drive, as on the late '90s engines.

[ 07-17-2004, 11:33 AM: Message edited by: gmctd ]

[willibig]

great information, I ordered a new high flow pump from Peninsular the other day i hope to get it soon so i can try it. It almost sounds like the problem could be not too much flow from the water pump but too fast making it lose flow from cavitation. This would make sense with a 373 gear and having the problem primarly at 65 mph or higher with no overdrive. I may try to find someone who can check if that is the problem i'am sure someone makes a machine that can test that.

Thanks for the info

[HammerWerf]

Willibig,

I just installed a Peninsular Hi Vol pump on my '83CC. Old pump locked up the bearing. Before I installed the pp, I reviewed this post, and followed the suggestions of GMCTD. I opened the driver side outlet till it matched the backing plate. Did you ever determine why your temperatures ran high at speed. My CC has 4.1 rear axle gear, so I am interested if a cause was determined? Radiator is brand new, replaced in Aug,05. This has been the year to do Cooling system fixes.

Hope the pump is working well for you.

HammerWerf.