Common cooling system leaks

[Gary Waugh]

Okay, my 08 expedition has covered 250K miles and is now loosing coolant, unfortunately there are no traces on the ground, leading me to suspect that it has a failed head gasket (coolant leaking into the cylinder and going out the exhaust), but I am not getting any error codes for misfire, etc and the cooling system is not showing any signs of being over pressurized, I would expect a leaking head gasket to either leak to the outside world (but no external signs of coolant), or the pressure from the cylinder to leak back into the coolant system and cause the system to blow out coolant from the expansion tank (no signs of this either!).
I am going to check compression on every cylinder, but the engine idles beautifully and smoothly. I wanted to ask what are the known weak areas on the 3V 5.4Litre V8 engine? I know there is a plastic T-piece just above the RHS cylinder heads that fails (I replaced this a few years ago), it seems like the thermostat housing (just aside/behind the alternator is also a known issue, but where else?
My garage floor is covered with rubber mats and any fluids show up very well, but after a 200 mile drive I often need to add 0.5 liters of coolant to the expansion tank, but I cannot see any drops on the underneath of the chassis and no signs of any fluids on the rubber mats. The T-piece is not leaking, I have cleaned all the dirt from around the thermostat and will keep an eye to see if I see any coolant (there weren't any signs of coolant, but after 18 years there was a lot of dirt and it was damp, so could be coolant), but open to any suggestions/ideas. Hoping to get another 100+K miles from the old girl.

Thanks for all suggestions, I did add Bars Leak-stop about 500 miles ago, but it had no effect on the coolant loss (I didn't expect it to, I think the leak-stops are all voodoo and don't really work), but would welcome any suggestions, hoping it's not a head gasket as that is more work than I really want to do at the moment..

Gary

 

[Fastcar]

Okay, my 08 expedition has covered 250K miles and is now loosing coolant, unfortunately there are no traces on the ground, leading me to suspect that it has a failed head gasket (coolant leaking into the cylinder and going out the exhaust), but I am not getting any error codes for misfire, etc and the cooling system is not showing any signs of being over pressurized, I would expect a leaking head gasket to either leak to the outside world (but no external signs of coolant), or the pressure from the cylinder to leak back into the coolant system and cause the system to blow out coolant from the expansion tank (no signs of this either!).
I am going to check compression on every cylinder, but the engine idles beautifully and smoothly. I wanted to ask what are the known weak areas on the 3V 5.4Litre V8 engine? I know there is a plastic T-piece just above the RHS cylinder heads that fails (I replaced this a few years ago), it seems like the thermostat housing (just aside/behind the alternator is also a known issue, but where else?
My garage floor is covered with rubber mats and any fluids show up very well, but after a 200 mile drive I often need to add 0.5 liters of coolant to the expansion tank, but I cannot see any drops on the underneath of the chassis and no signs of any fluids on the rubber mats. The T-piece is not leaking, I have cleaned all the dirt from around the thermostat and will keep an eye to see if I see any coolant (there weren't any signs of coolant, but after 18 years there was a lot of dirt and it was damp, so could be coolant), but open to any suggestions/ideas. Hoping to get another 100+K miles from the old girl.

Thanks for all suggestions, I did add Bars Leak-stop about 500 miles ago, but it had no effect on the coolant loss (I didn't expect it to, I think the leak-stops are all voodoo and don't really work), but would welcome any suggestions, hoping it's not a head gasket as that is more work than I really want to do at the moment..

Gary

No steam/white smoke out the exhaust? NO MORE BARS! Your liable to gum up a whole bunch of stuff.

 

[Gary Waugh]

No white smoke from the exhaust when starting or running!!
I have always noticed that the top passenger side corner of the radiator (when looking in through the front ford chrome grill) always seems damp, so I thought it could be a leak in the radiator, but I started removing the front of the car to access the radiator and found that there are 3 radiators, a small one running horizontally across the radiator (I assume its a transmission cooler) then behind that is a large radiator (the one that seems damp) but when I follow the lines connecting the radiator they seem to go to the power steering pump or AC compressor (oil level in the oil reservoir tank is good), so I assume the radiator is for the steering/AC (it seems very large) and then behind the 2nd radiator is a large 3rd radiator which connects to the coolant lines for the engine (cant see any damp spots on the 3rd radiator).

I wanted to run a cooling system pressure test, but all the kits I see, need me to connect the tester to the radiator pressure release cap, but I can't find one on this car!! Can anyone tell me if there is such a thing and where it is hidden? I guess I could try pressurizing the expansion tank, but that won't do much if there is a pressure cap somewhere in the system (between the engine and the expansion tank)!! How do you run a cooling system pressure test on a Gen3 (5.4L V8) expedition?

 

[AWAR]

The only radiator cap is the one on the plastic expansion tank. There is an adaptor for the Ford expansion tank. It would be less expensive to replace the cap than buying a tester. I have only had coolant leaks at the water pump, the heater hose “T” or the vacuum shutoff valve.

The leak you see through the grill is the power steering cooler. It is part of the air conditioner condenser. It is the top two or three rows of that unit. I have had a fleet of Ford pickups and all of those have had that same leak. On the last two we did I purchased a small stand alone cooler and bypassed the leaking cooler rather than replacing the condenser.

 

[Gary Waugh]

The only radiator cap is the one on the plastic expansion tank. There is an adaptor for the Ford expansion tank. It would be less expensive to replace the cap than buying a tester. I have only had coolant leaks at the water pump, the heater hose “T” or the vacuum shutoff valve.

The leak you see through the grill is the power steering cooler. It is part of the air conditioner condenser. It is the top two or three rows of that unit. I have had a fleet of Ford pickups and all of those have had that same leak. On the last two we did I purchased a small stand alone cooler and bypassed the leaking cooler rather than replacing the condenser.

Many thanks for that information, I was going to try and borrow a tester from autozone, but you have really helped by explaining the function of the second radiator. If it was a bad radiator cap I would expect to see coolant in the drain pipe above the pressure cap, but the pipe appears completely dry. Will try a pressure test as it shouldn’t cost anything and if I find nothing, I will change the expansion tank pressure cap. I will also try to get a better look at the water pump, but it seems very difficult to access or see.

 

[AWAR]

Crawl under and look at the bottom pulley and the balancer behind it. If they are white and a little crusty that is what the Gold antifreeze looks like when dry. The water pump would leak directly on that pulley and balancer if failing.

 

[Gary Waugh]

Well I managed to loan a coolant pressure tester from AutoZone and when I bring the pressure above 12 psi, I get loads of water leaking from the radiator, below 12psi it doesn’t seem to leak. The radiator has horizontal metal cooling fins with plastic caps running vertically at the left and right sides of the radiator. The 2 leaks are where the plastic caps join the metal cooling fins. I can’t complain, the radiator is 18 years old, but what a fight to get it out.. I can get a new radiator from Amazon (unknown brand) for $130 or AutoZone has a replacement for $300. Whilst the Amazon is probably not as good as the AutoZone part, I am planning to scrap the car in 5 more years (it will have 300+K miles) so I am thinking of going with the Amazon part in the hope that it will last 5 years. I will see what arrives from Amazon, if it doesn’t fit or just seems too weak or poor quality I can return it and get one from AutoZone. Can anyone tell me where the filler is for the transmission system? The radiator has a transmission cooler in it, so I have disconnected that but lost about 0.5 liters of oil, so I need to add that back into the transmission once I have connected up the new radiator. I can look in the manual, but thought I would ask here in case anyone can tell em where the filler port is for the transmission.

I have been looking for months to find the leak, I was amazed how easy it was to find with a pressure tester, most leaks in the past have been easy to find by looking where the coolant was collecting on the ground, but this leak never left any coolant when the car was parked, I guess because it only leaked when the pressure was over 12psi meaning the engine was working, not just pulling into the garage! Think I might actually buy myself a pressure tester for the future!!

 

[AWAR]

Your car should have a 6R80 if it is like the 08 pickups. They do not have dip sticks like the older transmissions. We attached a piece of fuel hose to a small funnel and added oil that way. There is a plug that screws in where the dip stick/ filler tube should be. Passenger side near the front of the transmission. 1/8” from a catalytic converter, don’t do this part when stuff is hot.

 

[Gary Waugh]

Many thanks Awar, everything will be cold so no fear of burning myself. Will take a look tomorrow and see if I can find the plug.

 

[Gary Waugh]

Can anyone confirm, I should be using Mercon V transmission fluid? It is a 6R80 transmission. The fluid in the transmission is dark red, same color as my Mercon V bottle, but just wanted to confirm.

 

[AWAR]

We use Mercon LV in 6R80 transmissions

 

[Gary Waugh]

Thanks again AWAR, I will go and buy some Mercon LV just to top it off. I also realised I can add the oil to the transmission by just putting a small funnel on the top line going to the radiator and pouring the oil into the funnel, it will just run down the line to the transmission, then I can connect the line to the new radiator. Much easier than removing the plug that you told me about

Regards Gary

 

[AWAR]

You’re welcome.

 

[Gary Waugh]

Well the cheap radiator that I ordered from Amazon never arrived, they claim it was damaged in shipment and returned to the sender. Amazon issued a full refund, so I ended up going to AutoZone and getting one of their radiators with a limited lifetime guarantee. Fitted the new radiator, the pressure cap is rated at 16psi, so i pressurized the cooling system to 20psi to allow for any inaccuracy in the pressure release cap and to give some margin, left the system for 45 minutes and the gauge did not move at all, so I now have a wallet that is $400 lighter, but a non-leaking coolant system. The manual states the coolant system needs 28 litres of coolant, but mine only needed 15 litres to refill it, I guess all the rear heating system failed to drain when I removed the main radiator.
Anyway job all done and hopefully the car should be good for a few more years, so happy to find it was the radiator that was leaking and not a head gasket or water pump!!

 

[Fastcar]

You might want to check the level a couple of times in case of trapped air.

 

[Gary Waugh]

I have left the engine running for about 20 minutes with the pressure cap off and all the heating controls set to maximum hot temp to try and get most of the trapped air out of the system, but will also check it regularly for the next few trips to make sure the level doesn’t drop..

 

[drankinatty]

Yep, usually the trapped air is displaced during the cool-down cycle overnight. (PV=nRT). So check it in the morning. I just drained the radiator on my 05 to remove the upper hose and heater hoses for a timing chain/phaser job. I had to repeat the run up to temp, cool down overnight, add 8-16 ounces to bring the level to full twice before all the trapped air was finally displaced. (things were much easier when you had the cap on the radiator, and could just look at the flow

Make sure you turn the heater ON to ensure the heater-control valve is pulled open to circulate coolant through that leg of the system. If I recall, the default bleed through the valve when closed to ensure some circulation -- isn't much, so that is a candidate for where a good amount of trapped air can reside. (especially if your 08 is like the 05 with the heater-control value mounted high on the passenger side of the engine above the fuel-rails.

Glad you got it sorted.