Hello!
I am a new owner to a 2000 Disco II V8. I have been reading the RAVE, and it seems the previous owner has made a plumbing modification to the cooling system. I have read many forum posts on the cooling system and the heater. I read about and have tried a couple simple procedures to try to get any potential air bubbles out of the system, and there don't seem to be any. I have a couple questions about the previous owner's slight modification to my cooling system. Also, I wonder if I have a head gasket leak.

I have the following conditions:
1. Coolant appears to be overly diluted green.
2. Bubbles in the expansion tank from Throttle Housing Return Pipe (traced in red below).
3. White Smoke from exhaust.
4. Heater works OK, but never gets super hot.
5. Engine runs well, and temp gauge does not rise above mid-level.
6. Outdoor temps at 30-40 degrees F.


7. I discovered that the previous owner has bypassed the throttle housing from the system entirely. See the pictures below:







Questions:
1. Is my Throttle Housing Return Pipe currently connected directly to my Manifold Outlet Pipe?
2. Do I need to correct this condition, re-plumbing lines to include the Throttle Housing, or is it ok the way it is?
3. Does that coolant look ok?
4. Does it seem like I have a leaky head gasket?

Many thanks to you! This is an awesome forum.

 

Unless you live in a region that typically experiences sub zero temps you do not need the throttle body heater. You can get a tester at autozone to test the coolant. If the white smoke is when cold only, that's normal. If it still has white smoke after about 15-20 minutes then you may have blown hg. There are several test you can do to determine if it has a blown hg. There are chemical test but they are not always indicative. You can rent a cooling system pressure and see if it will hold pressure overnight. However It is easiest to drive it a little while to see if it uses coolant. Run your bottle cap one turn loose until you determine definitively if the HG is leaking, leaking hg are known to pressurize the system and blow off hoses or crack bottles or radiators. Also be sure to keep it full of coolant and you should not have a problem wiht it overheating. The temperature gauge will not budge from mid zone until 240 degrees, forum members swear by the ultraguage or the torque app with an elm327 for monitoring temperatures. If you intend to keep it regardless of HG condition you should replace all cooling system components that are less than 10 years old - hoses, water pump, radiator, bottle, everything. Based on the look of your bottle it is quite old. You shoudl also do the PCV mod and hte inline thermostat mod asap. Also check the front driveshaft for grease fittings on the double u-joint flex joint near the transfer case.

 

Extinct,
Thanks a lot for that great info and your prompt response! Front drive shaft replacement and rear rubber flex disk replacement are on my list for next week. Also, I found the forum post for the "Best4x4 V288/FV308 PCV Install " - Great!

The white smoke goes away after the engine heats up. Also, I don't think I'm losing any coolant, but I will keep an eye on it.

The only remaining puzzle is why is the expansion tank is bubbling like crazy from the Throttle Housing Return Pipe?

Also, the engine is much louder on the passenger side for some reason.

Also, is this the thermostat I need?
https://lucky8llc.com/collections/di...emp-thermostat

Also, could bypassing the throttle housing coolant hose connection affect fuel economy?

Thanks again!

 

I have to ask where are you and are you sure the smoke is not just condensation burning off the inside of the exhaust system

 

Richard,
I live in Kentucky. It's been 30-40 degrees F here. I hope you're right and the smoke is just condensation burning off! The smoke stops after the engine is warm. But, I'm still wondering why I have a lot of bubble activity in the expansion tank. Also, my heater works but it doesn't get as hot as I think it should.

 

Well bad head gasket tend to blow white all the time. But 30 degrees F you will get white of the exhaust. The main difference is head gasket tend to be thick or really dense smoke, and generally it stays enve when you are warm.

Coolant motion in the tank is normal, coolant returns via an overflow line and the throttle body line

If you have actual "air" bubbles that is a much bigger issue

If you think you are getting over pressure:

• Put plastic bottle into the area are the jack goes make sure it is clean and dry
• Get some rubber line
• Attach it to the coolant bottle overflow line
• Stuff the other end into the plastic bottle and go for drive

If there is coolant in the bottle you have an over-pressue problem, if not you are unlikely to have a head gasket leak effecting the coolant. You could still have a head gasket issue but it is unlikely of very small.

 

Richard,
Thank you! I will try that test. All of the bubble motion is coming from the throttle body line, for what that's worth.

 

Maybe there's a leak in the bypass that the previous owner did, and air is being sucked in rather than coolant seeping out.
The issue with the heater being cooler than expected could be air trapped in it, or a dead thermostat. Or the vent doors for the HVAC system aren't working correctly.