Stohr coolant loss problem

[Ivinsea]

At my first race last week, my car consumed 1 quart of coolant during the 10 minute pre-race practice; after the 25 minute race, it consumed 3 quarts which means it was nearly dry. I cannot see any evidence of leakage beyond a small spot of coolant in the trailer.

Coolant is distilled water and water wetter.

Max water temp was 215. The sensor is in the radiator.

I find it hard to believe that 215 water temp. would boil out that much coolant, so I am thinking a head gasket problem.

I'll do a leakdown test ASAP.

Do you guys have any suggestions?

Thanks in advance.

[Wren]

The max temp was probably 215 because it couldn't make any pressure to go higher than 212*

I would guess coolant leak. Get a cooling system pressure checker and find the leak.

It was probably dry because the low pressure behind the car sucked the water out and dried the car. I have seen it before.

[RussMcB]

I agree with Wren's suggestion about the cooling system pressure tester. It is a great tool. I have used mine many times in the past 15+ years.

There are also test kits for checking to see if you have a combustion leek into the coolant system.

[Wright D]

I got creative and turned my leek down tester into a coolant system pressure tester. I took and old rad cap and modified it a bit so that I could hook up my leek down tester. I set the pressure in the leek down tester to 22 psi and plug it on the rad rap... I also use the leek down tester to test oil lines, fuel lines, oil coolers, you name it.

[martyb]

When we first received our Stohr F1000 it would pump water out like crazy (this was a dry sump motor with an electric waterpump). I was getting really good at replumbing it between practice sessions and moving the water pump around. The final solution was ridiculously simple; we had to raise up the swirl pot so that the bottom of it was higher than the top of the radiator. We moved it to as far forward and as high as would fit under the engine cover, and it stopped being an issue.

Marty

[glenn cooper]

Although it sounds simple, I have to ask - You did inspect the engine oil to ensure the leak is not internal? Oil would then resemble an Arby's Jamocha shake.

[Ivinsea]

Thanks for all the suggestions guys.

My dad tested the radiator cap - it is good to 21 psi.

Then he tested the cooling system - it held 23 psi for 10 minutes. Of course the thermostat is closed - do I need to warm up the engine so the themostat is open and then pressure test the system?

Glenn - the oil in the sight glass looks normal....

[PaulT]

Whether the thermostat is open or closed will not make a difference in pressure testing the system. It will keep coolant from flowing, but the pressure will "push" both in the normal direction of flow and in the opposite direction simultaneously.

Paul

[formulasuper]

The coolant could be leaking into a cylinder from a bad head gasket/warped head or cracked head & blowing out with the exhaust in the form of water vapor. Wouldn't necessarily get into the oil. A leak can occure when the engine is at operating temp but check good with a pressure tester when cooled down a little. Also, are you getting any coolant in your overflow catch tank?

[Ivinsea]

The coolant could be leaking into a cylinder from a bad head gasket/warped head or cracked head & blowing out with the exhaust. Wouldn't necessarily get into the oil. Also, are you getting any coolant in your overflow catch tank?

No, there is no water in the catch can. I don't know where the water is going....

I think a leakdown test is the next step.

[ghickman]

No, there is no water in the catch can. I don't know where the water is going....

I think a leakdown test is the next step.

Purple Frog is most likely correct. You may not see the water mixed with the oil as it is blowing it out the exhaust. I've seen this happen many times.

I believe with all that you have described that you have a blown head gasket. A pressure check thru the cap on your cooling system is the best way to test this. However it may not tell you what you need to know.

There is a dye that you can get at NAPA and some highend autoparts stores. You add it to the coolant and run the engine, if there is combustion leaking into the water it will change color.

GH
FB #76

[formulasuper]

Purple Frog is most likely correct. You may not see the water mixed with the oil as it is blowing it out the exhaust. I've seen this happen many times.

I believe with all that you have described that you have a blown head gasket. A pressure check thru the cap on your cooling system is the best way to test this. However it may not tell you what you need to know.

There is a dye that you can get at NAPA and some highend autoparts stores. You add it to the coolant and run the engine, if there is combustion leaking into the water it will change color.

GH
FB #76

Hey Gary, who the heck are you calling a Purple Frog??? Talk about a low blow!

[Nardi]

I've been through similar situations of no evidence of ' where did the water go'. The leakdown did confifm head gasket issues. The water level in the swirl pot started rising up ever so slightly. No bubbles. Just rose up very slowly. Pretty cool in a really depressing way.

[ghickman]

Hey Gary, who the heck are you calling a Purple Frog??? Talk about a low blow!

Sorry Scott....I should have known the Frog would never say anything that mechanically made sense...LOL

GH

[RussMcB]

That's funny you got those two mixed up. One is an old geezer, races on a ridiculously low budget, constantly talks about the good ole days of racing, tends to crash a lot and spends too much time on the interweb. The other is, well, umm. Wait. I've forgotten where I was going with this. Was I describing myself?

[sportech]

If you have coolant leaking into the combustion chamber look for a clean spark plug! The water steam cleans the plug. Dave

[Ivinsea]

Just got the leakdown tester.

What is the best way to determine top dead center?

Thanks all.

[formulasuper]

Just got the leakdown tester.

What is the best way to determine top dead center?

Thanks all.

You find the compression stroke by holding your thumb over the spark plug hole, then screw in the adapter & while one person starts applying a small amount of air pressure to the cylinder the other guy moves the propeller back & forth to feel top dead cen.......
Oh ya, were not working on airplanes anymore!

[glenn cooper]

This is a pretty easy job.
Remove cooling system cap and engine oil fill cap on clutch cover.
Pull all 4 plug cap/coils, and all 4 sparkplugs.
Take the inspection cap off the right crankcase/crankshaft cover, exposing the 14mm hex bolt head into end of crankshaft.
Install leakdown tester hose into #1 sparkplug hole, make sure regulator is backed off, and hook up air supply.
Get a socket and drive on the crankshaft bolt head and dial in 20 psi to the tester, and into the cylinder, all the while holding onto the ratchet, which will try like hell to bean you in the head, during this whole operation, if you let it.

As you turn the socket clockwise, you'll be turning the engine in normal roation and will soon enough feel resistance as the intake valve closes and you are now pushing the piston up on the compression stroke.
Hold onto the ratchet handle very tightly ensuring that your fingers and hands don't get wacked if it comes loose or whatever.

As you turn the socket more, the piston will rise; nearing TDC it will be sort of hard to hold it there, a touch too much and it will go past TDC and the air will then force the piston down, at which point you'll feel a huge reduction in effort to hold the ratchet.
There are also marks on the crankshaft inspection cap area that are spelled out in the servivce manual.

As you are holding the ratchet at a tic under TDC, check the gauge and see how much air is leaking out.

The air should be bale to be heard leaking from one of 4 places:

Oil fill port or crankcase vent - air is getting past rings and into crankcase
Intake port - air is getting past an intake valve not sealing or bent
Exhaust port - air is getting past an exhaust valve not sealing or bent
Cooling system/rad cap - air is getting into cooling system, suggesting a bad head gasket.

[Nardi]

I stick a thin rod in the spark plug hole and hold it between thumb and pointer finger with one hand. With the other hand I turn the engine via a wrench on the easiest to reach engine pully in motor rotation direction. Rod will move up or down or not at all when on TDC. Then I install leakdown tester. If at TDC, test works. Otherwise engine turns over. Try again. I always keep my hands, fingers, etc out of harms way when doing this. Do not get the bright idea of putting the car in gear to help hold the piston at TDC. You will not like what happens. However it makes for a great laugh for someone else watching!

[blackbmwk1200r]

As others have indicated TDC at the end of a cylinder's compression stroke will be where both intake and exhaust valves are closed. Therefore with the other sparkplugs removed and the testing cylinder pressurized through the sparkplug hole you will feel increased resistance due to air pressure build up when rotating the engine and getting close to the right point to test (TDC). I switch over to a breaker bar on my socket as I get close to top dead center to keep from going past and then move the breaker bar back and forth a bit until I get the best result on the leakdown tester which should be at TDC.

[formulasuper]

As others have indicated TDC at the end of a cylinder's compression stroke will be where both intake and exhaust valves are closed. Therefore with the other sparkplugs removed and the testing cylinder pressurized through the sparkplug hole you will feel increased resistance due to air pressure build up when rotating the engine and getting close to the right point to test (TDC). I switch over to a breaker bar on my socket as I get close to top dead center to keep from going past and then move the breaker bar back and forth a bit until I get the best result on the leakdown tester which should be at TDC.

Ya, breaker bar, that's the ticket. Not as easy as a 6 foot long propeller but works just the same.

[Ivinsea]

OK, so I did a cold leakdown test and at 100 psi, cylinders 1, 2 and 3 were at 98% and #4 was at 82% with a hissing sound out the exhaust pipe. I was surprised about the exhaust valve leakage. (Glenn - thanks for your detailed notes about leakdown testing.)

However, both Stohr and the incredibly knowledgeable Gary Hickman did not seem concerned about the cold leakdown test, and suggested the following tests:

1) Combustion Leak Block Tester (NAPA BK 700-1006) This is a test kit consisting of dye in a glass test tube. You run the engine and plug the test tube rubber stopper into the swirl pot. The test tube has a valve in the bottom to allow coolant vapors to pass through the test tube as you pump a bulb. If combustion gas is present in the coolant as in a blown head gasket, the dye changes color from blue to yellow.

2) Hot leakdown test.

3) Hot cooling system pressure test.

The combustion test did not indicate a blown head gasket; whew!

The hot leakdown test was 98% in cylinder #4.

So now I am trying the hot cooling system pressure check and the darn plug keeps popping out of the swirl pot when the pressure gets above 20 psi. We'll get it to stick somehow.

So at this point, the head gasket seems fine.
I do not think the car is overheating since the temps are not that high and the catch can is not getting any coolant.
So it seems likely to be a mechanical leak in the cooling system. Gary suggested that the radiator may have a leak at operating temps, perhaps where the header tank is attached with epoxy.

I am hoping to be able to race Sat....

[Wren]

So at this point, the head gasket seems fine.
I do not think the car is overheating since the temps are not that high and the catch can is not getting any coolant.

these engines have a 180* thermostat on them. I would be terrified if one started consistently running above that.

[RussMcB]

Have you done the cooling system pressure test with the engine running at operating temp?

[racer27]

I am hoping to be able to race Sat....

Bring some PC7 or Marine Tex epoxy and we'll see you Sat.

[Ivinsea]

Have you done the cooling system pressure test with the engine running at operating temp?

Russ,
I haven't tried that.

Should I pressure test hot/engine off and hot/engine running?

[RussMcB]

I can't think of a reason why you can't or shouldn't run the engine while the pressure tester is connected and providing pressure. I'd try it because that's about the closest way for you to simulate the conditions where your engine loses water.

Keep an eye on the pressure because it could rise as the water heats. There will be no way for it to escape without the regular rad cap in place.

[glenn cooper]

I think I recall you saying you had the rubber cone style psi tester, not the kind that attaches to the swirl pot just like the cap does.

You might want to get the good kind, cause that cone just might come shooting out.
Maybe want to wear an asbestos apron, AND eye protection!

[RussMcB]

Hm, I never knew about the cone type. This is what I have: http://www.stant.com/index.cfm?location_id=183

[Ivinsea]

The water pump was the culprit. The pump bolts to to engine block with 2 screws (!) and has a machined snout with an o-ring that presses into the block; there is a little drain hole approx 1/8" dia in the snout that probably is a drain hole; there were some water marks indicating a leak. I replaced the pump and the leak is gone.

Some knowledgeable people said they have never heard of a water pump leaking before....

Thanks everyone for your help.

[glenn cooper]

is the "tell tale", placed there purposely, so that in the event of the internal seal failing, coolant will drip out of that hole, alerting you to the fact that the pump is about to go Tango Uniform.