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Discussion Starter · #1 ·
Hello

I seem to have smoke coming form my expansion tank, to me it smells like exhaust but i could just be paranoid, several times recently the coolant has been forced out of the tank as the car almost overheated, carpets are wet so i am guessing o rings as referenced many times on this great site, could i loose enough coolant this way to cause an overheat?

if the coolant has been forced out of the tank would the cap be more susceptible to failure ? cause pressure issues within the cooling system as well.

there is absolutely no sign of any condensation on the oil filler cap and the head gasket was replaced (by me after the LPG system failed) only 1000miles ago, as i did the work i am not 100% confident it has been done correctly although i followed the book perfectly.

what are the other home test i could do to rule out HG and any other areas i could be looking at to test cooling system?

I read somewhere about the viscous fan failing how do you test this?

the car is an 1995 4.6 186000 miles on the clock (previous owner replaced engine at 120000 due to porous block issues back in 2002 i think)

need to be as sure as i can be that engine will be sound as i want to refit the LPG at great cost so i can use this car for a long time yet. i have no issues doing all the work i just help and pointing in the right direction

many thanks
 

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How is your cold coolant level? Yes, if it leaks enough coolant from the O-rings, and you don't keep it filled, you will eventually have an overheat problem. Did your temp gauge hit the red or did the warning light come on? If it's overheating you'll see it on the gauge.

There are test kits for testing for exhaust gasses in the coolant to help you tell if your head gasket is not sealing the cylinders from the coolant passages.

Brett
 

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Discussion Starter · #3 ·
Hi
Yes it hit the red once and the light came on but for a fraction of a second and then it backed off to about 3/4.
on the other occasions it has only gone up to 3/4 as far as i can tell. Coolant level when cold needs topping up quite a lot depending on how far i have been driving but i would say i have been loosing quite a lot.

i plan to get a test kit just to be sure but after further reading i feel that it must be a poor heater core, o rings filler cap etc all adding up to reduce my cooling capacity.

now the more experienced among you will be laughing and saying its the HG for sure but i love to be optimistic!

One more observation the two accessory fans right at the front never came on even when i had pulled over after it hit the red briefly and temp gauge had returned to 3/4 ! surely this is when they should be at full spin?
 

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1995-2002 Range Rover P38A
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A sign of failing head gasket is to feel main water pipes.
When cold start her up and note if pipes pressurize quickly.
Get a 2nd opinion if in doubt of fumes from tank, leak detector stuff is the best route.
You say that head job was done by you, depends on a number of factors....

New head bolts, this is a must
Quality head gaskets , installed correctly

Heads skimmed and pressure tested
Correcty tightening sequence

Engine coolant purged of air prior to starting

the list goes on
 

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Discussion Starter · #5 ·
Thanks for the testing advice

top hose stays soft until engine is up to temp even spread of heat throughout tube as well

as for the HG job yes all new bolts, correct order for tightening, hopefully a good gasket and yesthe air was purged

I will bypass heater core tomorrow while I wait to fix that but it's bloody cold here so need to fix soon but this should hep diagnose and I will pull all the spark plugs tomorrow and check for signs of steam clean
 

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I am going through this right now with my rig, its overheating and its 32F outside.

My theory is that you have a bad thermostat. Your leaking o-rings cause the cooling system to loose pressure, which lowers the boiling point of your coolant. Once you reach the flash point for boiling, the coolant expands and you get coolant coming out of the overflow and air in the system.

The thermostat is supposed to direct flow to your radiator once it heats up. If its not doing its job, you have no capacity for cooling the engine except what little amount the heater core can handle.

Q's: Have you noticed your heat being extremely hot? Have you noticed if your temp gauge reading is affected by what setting you have your heater on?

Also the accessory fans in the front only come on with the AC.

I would replace your thermostat Before you bypass the heater core. If it is a bad thermo, without the heater core, it will over ehat immediately.

This is just the theory i'm going on with my rig, still waiting for a new thermo to test it out.
 

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Discussion Starter · #7 ·
pdxRR

Good theory, i tested it out today, removed the thermostat ran boiling water through it, it took some persuasion from lots of boiling water before it opened, is this normal?
before i did this i bypassed the heater core (as i know its leaking badly) and took the car for a test drive, 15min of driving and the temp gauge started to climb fortunately i was very near to my home so parked up and let it cooled down.

this does seem to agree with your theory hence the removal of the thermostat for testing. Also when it last nearly over heated i nursed it home with the heater on Max and revs below 2000 and the temp gauge stayed in middle for 100miles of the remaining journey.

Still going to replace expansion filler cap just to be sure. But how do i test the viscous fan, i can spin it in both directions by hand when the engine is off, is this normal or should the be some degree of resistance?

Also i removed all the spark plugs today and no sign of any steam cleaning they all looked normal (except no 8 which looked a little oily) and there is definitely no condensation on oil filler cap so i am hopeful that the HG is fine and all my problems lie with the dodgy cooling system
 

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I'm not exactly sure how you test the viscous fan. Supposedly there is oil or some fluid inside the fan bearings that stiffen when hot acting as a sort of clutch. I would presume that when the engine is hot, the fan is stiffer and more difficult to turn when the engine is off? Maybe search the forum, or perhaps someone more knowledgeable could chime in here.

I took my thermostat off yesterday, hoping that i may be able to remove the bits inside to open the flow up. What i ended up doing was stuffing some copper wire inside to hold that spring loaded diaphragm in the open position. I was able to twist the end of the wire around a stationary part of the thermostat inside, so as not to loose the wire inside the engine. I let the car idle for 30 mins and have been driving it today with no problems at all, it doesn't even get warm enough to reach 10:30 on the temp gauge. I figure this will hold me over until my new thermostat arrives tomorrow.
 

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You can ping the radiator with an IR thermometer. If the radiator is "cold" when the engine is hot, there is no coolant running through it (or not enough). Does sound like it could be a bad thermostat. If coolant is too low, the pump will cavitate and will no longer pump coolant through the block, and it will overheat. If it's overheating with full coolant, then thermostat is a good suspect.

I'm not sure that pouring water over the thermostat is the best test. It's slow acting. Better is to immerse in hot water for a period of time. But, it's cheap enough to just replace it and see what happens.

Brett
 
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