coolant loss

[rhtrudder]

I reckon I am loosing a small amount of coolant out of the expansion bottle , searched ever where but it doesn't show up , is it possible to hand pump some pressure in through the hose that feeds the bottle to check if that shows up anything .

 

 

[cscotthendry]

Hi:

 

You didn't mention what type of engine, or how much coolant you had to start with in the overflow bottle, or how much you have lost and over what length of time, but I'll have a little stab at this.

 

The amount of coolant in the expansion bottle should be between the minimum and maximum levels indicated on the bottle. If you check the collector tank at the top of the engine (I'm assuming a Rotax engine here) and it is full to the neck, then I'd lean towards having the coolant in the expansion bottle nearer to the minimum level.

 

Pressurising the line between the collector tank and the expansion bottle won't really tell you much. There's never any pressure in that line even when the engine is working hard and some coolant expands into the bottle. The top cap of the expansion bottle should have an air hole in it so consequently there is never any pressure in the overflow line or bottle.

 

Things to check: (Again assuming a Rotax engine.)

 

1) There is no air in the engine. Do this by removing the collector tank cap (cold of course) and lifting the collector tank as high as the hose connections will allow so that any air in them will migrate into the tank. Give each hose to the heads a little squeeze while you're doing this to encourage any bubbles up into the tank. When you're finished with this, make sure the tank is full right up to the neck with the correct coolant.

 

2) Check the seals on the tank cap for ageing or nicks. The tank cap causes a slight pressure buildup in the cooling system in the engine which raises the boiling point of the coolant. If the cap is not sealing, then that pressure won't build up and under the right conditions localised boiling can occur in the cooling system, which causes steam bubbles which will push extra coolant out into the overflow bottle.

 

3) Check that you have the right coolant tank cap for the coolant you are running. I think there are different caps for Evans coolant and for glycol based coolants, but I could be wrong here. If there's any doubt about the status or condition of your coolant tank cap, buy a new one. They're not that expensive.

 

4) If you can find out what the tank cap pressure rating is, see if you can get someone with a cooling system pressure tester. It's a little gadget that clamps on in place of the tank cap and has a pump handle to pressurise the system. Pressurise the system to the cap rating and hold it there and see whether the pressure leaks down. If it does, you have a coolant leak somewhere.

 

5) Check under the engine where the coolant pump is for signs of coolant leaks. Coolant pump seals work very hard under heat and pressure. They are prone to failure.

 

6) Check all your hoses for signs of coolant leaks. I put this last because, a leaking hose will more than likely lose coolant at a huge rate of knots, not just a little loss now and then.

 

 

 

[johnm]

The following suggests unsound mathematical advice: ...........Yes - that said rotax hoses to be replaced at 5 years .......... you can probably stretch it to say 7 years if you are not good at counting

 

 

[rhtrudder]

Hi:You didn't mention what type of engine, or how much coolant you had to start with in the overflow bottle, or how much you have lost and over what length of time, but I'll have a little stab at this.

The amount of coolant in the expansion bottle should be between the minimum and maximum levels indicated on the bottle. If you check the collector tank at the top of the engine (I'm assuming a Rotax engine here) and it is full to the neck, then I'd lean towards having the coolant in the expansion bottle nearer to the minimum level.

 

Pressurising the line between the collector tank and the expansion bottle won't really tell you much. There's never any pressure in that line even when the engine is working hard and some coolant expands into the bottle. The top cap of the expansion bottle should have an air hole in it so consequently there is never any pressure in the overflow line or bottle.

 

Things to check: (Again assuming a Rotax engine.)

 

1) There is no air in the engine. Do this by removing the collector tank cap (cold of course) and lifting the collector tank as high as the hose connections will allow so that any air in them will migrate into the tank. Give each hose to the heads a little squeeze while you're doing this to encourage any bubbles up into the tank. When you're finished with this, make sure the tank is full right up to the neck with the correct coolant.

 

2) Check the seals on the tank cap for ageing or nicks. The tank cap causes a slight pressure buildup in the cooling system in the engine which raises the boiling point of the coolant. If the cap is not sealing, then that pressure won't build up and under the right conditions localised boiling can occur in the cooling system, which causes steam bubbles which will push extra coolant out into the overflow bottle.

 

3) Check that you have the right coolant tank cap for the coolant you are running. I think there are different caps for Evans coolant and for glycol based coolants, but I could be wrong here. If there's any doubt about the status or condition of your coolant tank cap, buy a new one. They're not that expensive.

 

4) If you can find out what the tank cap pressure rating is, see if you can get someone with a cooling system pressure tester. It's a little gadget that clamps on in place of the tank cap and has a pump handle to pressurise the system. Pressurise the system to the cap rating and hold it there and see whether the pressure leaks down. If it does, you have a coolant leak somewhere.

 

5) Check under the engine where the coolant pump is for signs of coolant leaks. Coolant pump seals work very hard under heat and pressure. They are prone to failure.

 

6) Check all your hoses for signs of coolant leaks. I put this last because, a leaking hose will more than likely lose coolant at a huge rate of knots, not just a little loss now and then.

 

[ATTACH=full]52308[/ATTACH]

Thanks for all your advice, I borrowed a radiator pressure testing outfit from a mate but none of the caps were small enough to fit the Rotax header tank so I figured I could pump some pressure back down the bleed off hose which should open the non return valve in the cap and end up in the system which hopefully might show up any leaks unsure whether this is the right way to go about it

 

 

[SSCBD]

The following suggests unsound mathematical advice: ...........Yes - that said rotax hoses to be replaced at 5 years .......... you can probably stretch it to say 7 years if you are not good at counting

DONT believe in hoses lasting that long, I have had them fail - (spilt in flight ) - I would change them personally every 3 or 4 years. Coolant also causes hoses to degrade and become brittle over time, I am told by a ford mechanic.

 

 

[skippydiesel]

........... Coolant also causes hoses to degrade and become brittle over time,..........

Sorry mate but your comment makes no sense and your Ford advisor is telling "porkies".

 

I have had automotive coolant hoses last in excess of 20 years without failing or going hard. I routinely replace my coolant at the required intervals at the maximum effective concentration (50:50) using good quality concentrated coolant mixed with rain water or in my Rotax, distilled water.

 

I replace my Rotax hoses at/about 5 years as required by "The Book" not because the hoses have gone hard (they have not).

 

If your coolant hoses are breaking down in under 5 years the likely reasons are one or more of the following:

 

• Your started with poor quality hoses - spend the money on quality hoses
   
   
  
• Your coolant is of poor quality - Purchase Rotax recommended coolant (Castrol) and mix with good quality distilled/deionised water @ the correct ratio
   
   
  
• Your coolant ratio is incorrect - 50:50,1:1, 1/2 & 1/2, call it what you will but this will give you the best mix of heat/cold/internal cooling system protection & seal lubrication.
   
   
  
• Your coolant hoses are being exposed to hydrocarbons such as engine oil/petrol - improve your maintenance/engine cleanliness.
   
   
  
• Your hoses run to close to unshielded exhaust pipes ie are being "cooked" by external radiant and/or convection heat - re rout your hoses and or shield the hot exhaust system.
   
   
  
• You are overheating your cooling system- clean your radiator core of chaff/insects/other blocking debris & make sure your in/out airflow is acceptable.Reduce your angle of climb/increase your climb airspeed & maintain a minimum of 5200 RPM in climb configuration. If using coolant, start by looking for leaks should not be hard to find as coolant at the correct ratio leaves "tell tale" deposits of chalky stuff. If no system leaks, try replace your "radiator" cap (cheaper if you purchase from Ducati motorcycle dealer). If you have a thermostat fitted, consider removing it (they are not necessary in most Australian climatic conditions)
   
   
  

 

 

 

 

[onetrack]

Chinese coolant hoses only last 4 or 5 years. Buy top quality coolant hoses, and they will certainly last 10-15 years without problems. Skippydiesel is on the mark.

 

Re the coolant loss; The OP hasn't indicated whether the coolant loss is purely from the expansion bottle - or from the cooling system overall. In other words, is he needing to top up the collector tank regularly?

 

It's extremely important to ensure the hose between the tank and the expansion bottle is totally sealed at every join in it (usually only two - at the tank neck, and at the expansion bottle).

 

If this hose has a loose connection, it may allow pressurised coolant to travel from the engine to the expansion bottle, without showing signs of leaking - but when the cooling system is cooling, and the system is sucking coolant back from the expansion bottle - the loose connection may allow some air to enter the cooling system.

 

Then, when the engine is run to operating temperature again, it's possible for the expansion bottle to overflow, as the engine coolant expands with the air in it.

 

If the tank isn't topped up regularly when this is happening, the end result is engine overheating, due to low coolant level.

 

 

[skippydiesel]

I have & continue to use Gates coolant and fuel hoses.

 

I know there are other reputable brands out there but I find that Gates products are readily available in my area (currently I purchase through Repco but have had other suppliers in the past).

 

My Gates rubber is still nice and flexible/soft without any sign of cranking when I do my 5 year replacement - this gives me peace of mind (I re use the "preloved" fuel hose on land based equipment.)

 

For my fuel, hose I prefer to use the fuel injection hose - Yes I know it is way over specified for the pressures likely to be found in a Rotax fuel delivery system but it makes me feel good to have "the best".

 

My small coolant lines are supplied by Floods/Rotax but the two larger bore hoses are Gates automotives pre shaped (from memory older Gemini car) that through experience/trial & error I have found will fit neatly with only one joiner per side, after cutting to length.

 

Couple of additional probably "analy retentive" additions -

 

• I use fuel injector hose clamps on all my fuel lines for a better more secure seal
   
   
  
• All my rubber assemblies (& subsequent disassemblies) are assisted by the addition of a very small smear of high quality silicon grease (Dow Corning Molykote 111)
   
   
  

 

 

Should you purchase through Repco, take my advise and negotiate hard for a lower than the recommended retail price. I have a good relationship with my local store and have regularly been able to get very large reductions even on ordered in/special products.

 

Further comment on coolant loss :-

 

It is normal/acceptable for a small amount of coolant to leak out of the coolant pump seal. When engine cool, get your eyes/hand on the bottom of the pump casing a small drop of green (if Castrol coolant) fluid is likely to be present. In my installation I will see about a 3mm drop in the coolant expansion bottle level over about 50 hrs of operation. To me this is acceptable.

 

Not sure if this has been mentioned - When engine cold, your overflow/expansion bottle should be between minimum and 1/2 full level . When hot the level must not rise above maximum. DO NOT OVERFILL the expansion tank. If you do fill above 1/2 full the excess coolant will be vented/lost. This does not mean the system in faulty.

 

 

[skippydiesel]

Having just completed my 912 ULS, 800 hr & 5 year rubber replacement, maintenance/ service, I just thought I might share my hose supply experience with you:

 

My coolant, fuel & oil hoses come from only two suppliers Gates (Repco these days) and Bert Flood.

 

BF supplies my oil & small coolant hoses.

 

Repco supply my Gates large coolant & all my fuel hoses.

 

Gates specifications & Part No are:

 

Fuel

 

27349 - 3/8 (9.6mm) Barricade Fuel Injector Hose

 

27348 - 5/16 (7.9mm) Barricade Fuel Injector Hose

 

27347 - /4 (6.3mm) Barricade Fuel Injector Hose

 

Above part numbers are for 15 ft length, however Repco will sell it to you by the metre. (The FI hose is about twice the price of ordinary low pressure carburetor hose)

 

I use proper fuel injector hose clamps for a good seal without damaging the hose.

 

My fuel filters are Hengst H 102 WK (for those who might want an inbuilt elbow, try H 103 WK)

 

Coolant.

 

Radiator hose 05-0725 (x 3) . Three of these Holden Barina MF 1.3 L 1989-90 upper radiator hoses do my installation very neatly with minimal cutting & only one joiner

 

Joiner 90 degree elbow 28626 (x 1). These joiners come in a pack of two. They may look similar to 1" plastic irrigation line joiners but are properly heat rated and tested for coolant compatibility.

 

Coolant concentrate is Castrol Radicool mixed 50:50 with distilled water.

 

If you want straight joiners the PN is 28606.

 

I have attached a photo of the coolant hoses with two other hoses I did not use.

 

The unused hoses are:

 

PN 05-1797 Subaru Outback 3.0L 6 cylinder 1988-04 Upper radiator

 

PN 05-1235 Ford Lazer 1994-96 Lower radiator