coolant pressure testing question..

**Stav** · 30-04-2007, 08:52 AM

Hi guys.I need to know something.If a car loses no pressure with coolant pressure test when cold does this mean there are no leaks? Or does there some hot pressure test need to be done? What are the procedures for testing leaks or is the cold test good enough?

**russellw** · 30-04-2007, 09:06 AM

Hi Stav

Generally a cold test is sufficient to check for coolant leaks. If you are losing coolant then there are other possible causes such as head gasket, water pump, cap that won't necessarily be picked up in a pressure test.

Cheers
Russ

NeishaXR8_347 · 30-04-2007, 09:18 AM

It depends on what type of leak you'r looking for, things like a tiny pinhole may only leak once it has some heat and things have expanded.

FGII-XR6 · 30-04-2007, 09:47 AM

i have an extremly slow leak from the passenger side header tank that will not show on a pressure test only just found it as there is now a white stain there only loosing 1L every 6 to 8 weeks could smell the coolant but couldn't see the leak so sometimes a pressure test won't reveal all :(

**Stav** · 30-04-2007, 02:59 PM

Ill fess up. I did a pressure test last night and left it. I started a 150 kpa and checked it 15 minutes later. It had dropped 5 kpa. I then left it overnight to find it at 135 kpa in the morning seven hours later.I spotted a coolant leak again from my head under intake runner 3. It was small.I ended up tightening the head bolts up to 100nm with my torque wrench and rechecked it.I started pressurising at 150 kpa and after 1 hour with the sun hiitting the engine bay the pressure rose by 1 kpa!! This lead me to think that if the coolant system is presure tested when hot them it would surely give a pressure drop as the coolant dropped in temperature.So I took my pressure gauge to work today and tested it again.The pressure dropped fast..very fast but coolant level did not budge. After 1 hour of not being driven.I tested again.The pressure was 160 kpa.I left it for 30 minutes and the pressure was held without a drop in the reading.It stayed at 160kpa. If this is the reliable indicator then the I have no fear of a head gasket leak..Am I correct?

FGII-XR6 · 30-04-2007, 05:04 PM

well i wouldn't say no fear sounds like there is a weakness with the head gasket but you have at least bought yourself some time i'd start saving for a head gasket and machine if I were you

Umineko · 30-04-2007, 07:58 PM

I'd second that, you had a coolant leak under the gasket, torqueing it down harder might stop things in the short term but the head is now under greater stress and the gasket is already compromised, might last you 6 months, might blow tomorrow... I'd start looking to get it machined and refitted ASAP.

**Stav** · 30-04-2007, 08:25 PM

The au headgasket is multilayered metal material.To destroy this gasket is not easy. The car is very cool. It does not overheat and does not loose any coolant in normal driving.

The leak only shows up at 150 to 140 kpa. The au radiator /resevoir pressure is 120. The other thing I noticed today is that my tester is leaking coolant..its stuffed. I wont be changing the head gasket unless there are some certain symptons.The car goes great, there is no water in the oil,there is no steam coming out of the exhaust except morning condensation.I have collected this water and it has no coolant..it is clear.

I am driving down to Victoria for the ford forums drag day 900 killometre trip with this car.

I will install the pressure tester tonight to see if anything else shows up.i am doing a 300 killometre round trip tommorow and I will see if the coolant drops at all and double check the prior head leak.

FGII-XR6 · 30-04-2007, 08:38 PM

i wasn't saying rip the head off now just advising that you ready yourself for the expense as this is not a cheap exercise to do properly. if your car is an AU2 the gasket is much better construction but if it is an AU1 and still the one it rolled out of the factory with the prognosis is not good. These gaskets are S$&T and do not last. ford finally woke up in the AU2 and fixed this problem I drive a cab with over 820,000 Ks on the original gasket but this is a S2 . hope you get a bit more time out of it though, good luck

mik · 30-04-2007, 08:48 PM

might be a water jacket leak stick some wynns stop leak (the best stuff imo)in it it will last for ages, the family runabout had a dodgey radiator 12 months ago and is still holding coolant no probs.

**Stav** · 30-04-2007, 10:03 PM

Quote:

Originally Posted by mik

might be a water jacket leak stick some wynns stop leak (the best stuff imo)in it it will last for ages, the family runabout had a dodgey radiator 12 months ago and is still holding coolant no probs.

will do.I think its a water jacket leak too.The car could last another 3 years with that. Then something newer and a full rebuild of the wagon with a twin turbo v8!!

ratter · 30-04-2007, 10:12 PM

You have now probabbly damaged the elasticity properties of your torque to yield headbolts by doing them up tighter than specified.

**Stav** · 30-04-2007, 10:23 PM

I know...thats what I wanted to do.Whats the point of elastic stretchy bolts? More leaks? I want the thing to seal down hard and never come off. I had the the first time head install done at my mate chiefs workshop.They did a great job. But we got haemoroids trying to get my old bolts off.They were so tight. I figured that if I retorque the head to this pressure that nothing will leak..and I think I am right on this one but well find out.

**aussiblue** · 30-04-2007, 10:29 PM

After the pressure test of one hour look inside the spark plug holes with a torch; you will often see coolant sitting on the piston crown(s) if the head gasket is gone. In any event, after leaving it pressurised for an hour turn the engine over with the spark plugs out and white paper towels over the holes; the papers towels will be stained with coolant when you turn the engine over if there is a leak into the cylinders.

**aussiblue** · 30-04-2007, 10:37 PM

PS a lot of leaks will only show when the engine is hot.

The instructions with cooling system pressure testers usually say screw it on cold then get the engine to normal operating temp and also rev the engine when hot to see if leaking combustion gases cause the pressure tester needle to fluctuate increase pressure momentarily. If the gout hadn't got me at the moment I would go up to my shed and get the word for word instructions for my Rex cooling system pressure tester.

Over-torquing the head bolts also risks them breaking when either you do that or you try to remove them.

Overheated cylinder heads will also often go soft as a result and flutter when hot (i.e. vibrate up and down against the head bolts at either end) and you will only pick this up on the hot engine.

**Stav** · 30-04-2007, 10:45 PM

I did a running test.With the engine warmed up install the pressure tester and if the needle fluctuates up and down its a head gasket to combustion chamber.If this doent happen rev the car and look for water in the exhaust .The needle did not fluctuate nor has there been any coolant out the back.. The car passed these tests when hot. Clear condesation only in the morning and ive checked it with white a4 paper.Grey rich splatter with clear water not green.

I am hopefull..it hasnt lost a drop in the level in the bottle since.

FGII-XR6 · 30-04-2007, 10:56 PM

thats the other issue with the head bolts once over tightened the can become brittle and crack as they expand and contract that is why the say to replace them when u do the head with any luck this won't happen to you as it's a pain if they snap @ block level

**Stav** · 30-04-2007, 11:20 PM

Quote:

Originally Posted by au3xr6

thats the other issue with the head bolts once over tightened the can become brittle and crack as they expand and contract that is why the say to replace them when u do the head with any luck this won't happen to you as it's a pain if they snap @ block level

Trust me they will not snap . In removing the first headbolts from the first removal the last 2 were really stuck!! They were hit with the oxy torch for 25 minutes and wouldnt break! Eventually 20 minutes each bolt with an angle grinder got them off. Those bolts are space shuttle proof.

FGII-XR6 · 01-05-2007, 12:00 AM

i've seen then snaped at block level and not from undoing them sometimes they become brittle and from my understandin it is from overtightening or reusing them i'm not saying this will happen to you just leting you know it can happen good luck

**Stav** · 01-05-2007, 07:03 AM

I know you mean well and I thank you for that..

ratter · 01-05-2007, 08:43 AM

Quote:

Originally Posted by Stav

. Those bolts are space shuttle proof.

That's not quite correct.
Torque to yeild bolts have 4 stages, elastic phase, yield phase, plastic phase and shear phase.
Unlike a conventional bolt, TTY bolts are tightened beyond their elastic range, past their yield range and into the plastic phase.The bolt is permantly stretched and it is for this reason they should not be reused. the reliability of these bolts once stretched is greatlt reduced.

**Stav** · 01-05-2007, 04:50 PM

I dont know champ? I do know that I went too Newcaste today from Merrylands for work and dropped off to bankstown in the meantime. I travelled about 370 killometres today. I emptied the coolant to the full mark exactly when it was cold last night.

I checked the coolant when I reached Newcastle/Wickham and it actually had gone slightly above the full mark. I can only imagine that this is typical expansion from heat. Also on the way up there the cars' temperature dropped from o to n on the normal range.

The car sat on 90 and acceleration to 110 kmph was just with very light force on the accelerator pedal.
The car has alot more power than ever.It feels amazingly smooth and it wants to go alot faster but speeding isnt safe so I keep it in check.

I just got home a few minutes ago and checked the coolant level.It was still above the full mark .I also have yet to see any visible head gasket leak where it was before.
It seems to be gone.It seems fixed. The bolts..if they break then it will give me a reason to rip the car apart.But they wont..I know they wont.At the end of their stretch they will be tight. That way I know that ill be avoiding to change a 3 week old head gasket from moron mechanics at a wrecking yard.

Now you know why I like doing it myself.

JC · 02-05-2007, 12:20 PM

Quote:

Originally Posted by au3xr6

i have an extremly slow leak from the passenger side header tank that will not show on a pressure test only just found it as there is now a white stain there only loosing 1L every 6 to 8 weeks could smell the coolant but couldn't see the leak so sometimes a pressure test won't reveal all :(

The passenger side header tank? That's the windscreen washer bottle. The radiator overflow/header tank on AUs is on the driver's side.

FGII-XR6 · 02-05-2007, 12:37 PM

Quote:

Originally Posted by JC

The passenger side header tank? That's the windscreen washer bottle. The radiator overflow/header tank on AUs is on the driver's side.

i mean the passenger side tank on the radiator JC

**Stav** · 04-05-2007, 04:48 PM

After much time spent looking at my water level today I purchased a block tester.This nice little tool verifies combustion gases in the cooling system. You stick the tester into the filler neck wit dye and pump it for one minute.After a minute if the dye turns yellow then you have a blown head gasket,cracked head or cracked block.If the dye stays its original blue colour then there is no leak from the combustion chamber.

The result was that the dye stayed blue.My caper seems to have worked.

Also I have done alot of research on tty bolts. Thses bolts can be retorqued to specifications on an allloy head when it is cold and on an iron head when its warm. I am taking a chance by the extreme torque I applied to the bolts but I will deal with it if it happens. For now my problem is fix and the car is running.I am losing a tiny tiny bit of coolant but it is definately not internal.