Mysterious leak.

Lyonmt · Aug 29, 2007

Hello All,

As you may (or may not) remember, I had a cooling system problem last week. See the thread here.

Well, I replaced the the thermostat with a 180 degree unit and I drilled a small hole in it first. I also just replaced the waterpump. I replaced the waterpump bypass hose. And lastly, I had replaced the heater bypass hose with a hose made specifically for that purpose.

So my issue is that I have a leak, because every day, when I check my coolant overflow tank, it is empty. Also, the radiator is always low on fluid. The car seems to run great for an hour, when the fluids are full, but then (obviously) gets worse at it loses coolant. Also, if it is full of coolant and I immediately take the car out and rip through the gears at 5500 rpm, the temps will shoot up to 220.

everyday I look for a leak and everyday I come up empty handed. I always look after a long drive and there is nothing! WTF?!?!

I guess I need to get some dye at the auto parts store, because it must only happen under pressure?

Any other suggestions would be appreciated.

Here are some pics for the heck of it!

91 HATCH · Aug 29, 2007

You need new head gaskets.

also that flex fan is hurting your power

bill302 · Aug 29, 2007

does the oil look like chocolate milk, do you have white foam under the oil cap? as hatch says above prolly need a headgasket..do not drive if you have any of the above symptoms because oil + coolant mixed = ruined bearings if driven...

Lyonmt · Aug 29, 2007

No milky oil, no oil in the coolant.

In Florida, with it being 95 degrees everyday on my hour commute home, I'll take the loss in power for the increased cooling, but thanks.

fastford91 · Aug 29, 2007

well the flex fan is 10 times better than the piece of crap clutch fan ford put in our cars.... but an electric one well now your talking ! anyway as for your coolant leak if its not leaking from where you've already fixed and replaced .. id do a compression test check for a head gasket ! but like you said there's no coolant in the oil! if the compression test #'s are OK id do the dye thing you were talking about! I'm guessing by the pics supplied that your car is mostly stock the engine isn't very clean either !! you might want to have it shampooed and check it again after a good cleaning! you cant see anything if its all covered in all that dirt grime and oil that's on there!!!! well those are my suggestions! I'm sure others might have more! but let us know what the cause is if you find it!

1.8kmint · Aug 29, 2007

Maybe its jsut me but that UV dye didnt do **** when I looked for my leak with the blacklight. I still havnt found the damn thing but maybe you will have more luck. My leak is alot smaller so it may show up better for you.

Lyonmt · Aug 29, 2007

fastford91 said:
anyway as for your coolant leak if its not leaking from where you've already fixed and replaced .. id do a compression test check for a head gasket ! but like you said there's no coolant in the oil! if the compression test #'s are OK id do the dye thing you were talking about! I'm guessing by the pics supplied that your car is mostly stock the engine isn't very clean either !! you might want to have it shampooed and check it again after a good cleaning! you cant see anything if its all covered in all that dirt grime and oil that's on there!!!! well those are my suggestions! I'm sure others might have more! but let us know what the cause is if you find it!

I'll do the compression test this weekend.

You should have seen that motor when I got the car last month! I gunked and power washed it at the (do it yourself) car wash and then power washed it again a few days later. I have to change the valve cover gaskets too, they are leaking badly. That will be done this weekend, as well as, a full tune up and a headliner. i bought that car for $2k, so you can imagine what is was like when I got it. In fact, you don't have to imagine, check my website: http://www.mtlsalesinc.com/the_mustang.htm

88mouse · Aug 29, 2007

They make a pressure tester for the rad. This way you can put pressure on the sys. and it won't be hot or anything. When you pump it up you will either beable to see where its leaking or if the pressure drops its most likly you have a blown head gasket.

jake2582 · Aug 29, 2007

88mouse said:
They make a pressure tester for the rad. This way you can put pressure on the sys. and it won't be hot or anything. When you pump it up you will either beable to see where its leaking or if the pressure drops its most likly you have a blown head gasket.

thats what i would do*

2_fast_4_ya · Aug 29, 2007

i would have to say if its leaking that much in that short amount of time its more than likely head gasket. 5.0's have tendacy to get a pinhole where it leaks coolant in the cylinder. i know this because my car has the same problem just not as bad as yours. and i have changed about 5 million.

Lyonmt · Aug 30, 2007

Can I just change the gaskets or is a resurface necessary?

Lyonmt · Aug 30, 2007

I FOUND IT!!!

It is the throttle body coolant line, down behind the intake manifold where it connects to the hard heater lines. I went to a local service shop to pressure test the cooling system. The local auto parts store didn't have one for sale. I guess it needed the pressure built up by the engine revving at higher rpms to force the fluid up and out of the line. I have to change the valve cover gaskets anyway, so I bought some new line to replace the old stuff that is in there. I guess I cracked the line from removing and replacing the upper intake manifold so many times when I was trying to repair the fuel leak.

fastford91 · Aug 30, 2007

good glad to hear you found it!! now tear that stocker outta there and build it up! LOL ! i know little things like that bug me to and i wont stop till i find it ! i know how madding that can make you! glad to hear its fixed up! now go shred some ricers!!

Lyonmt · Aug 30, 2007

fastford91 said:
good glad to hear you found it!! now tear that stocker outta there and build it up! LOL ! i know little things like that bug me to and i wont stop till i find it ! i know how madding that can make you! glad to hear its fixed up! now go shred some ricers!!

The stocker stays, as this is my commuter car. The built motor is in my Cobra (306). However, It does have intake and exhaust. So I need to take it to the track to at least find out what it can do. A guy I know wants to race me with his V6 camaro so I plan on doing that next week hopefully, if I get all of the bugs out.

Yes, maddening, I can't stand that kind of crap. I'll be happy to shred some ricers, but they always fly past when you aren't looking then quickly pull off.

Mustang78 · Aug 30, 2007

I had a small coolant leak, it was the upper heater core hose, just above the T-Stat. I looked all around but couldent find any evidence, Turns out it only leaked under pressure, and evaporated on the intake..

~Mark~

Mysterious leak.

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