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V8 coolant bleeding procedure?

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Could someone please help with the proper method of bleeding the cooling system in a V8? I don't have a service manual yet, but from what I understand, the manual gives a detailed procedure for removing air locks from the cooling system.

I've searched the forum and am not having much luck. I think I may have air in the system after replacing the thermostat.

I've looked for a bleeder valve at the radiator, but am unable to locate one. Was this feature only on the older models?

Thanks so much!

-Mike

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Bleed for the radiator is ot the top at the left hand side. Do this first the keep topping up the header until all air is out. Then run the engine and take out the bleed screw on the alloy pipe at the front of the engine. Once warm air will escape here. Replace the bleed screw and run the engine up to temp (heater on) and check all is ok. Leave to cool and bleed rad again.

Trevor.


I'll get around to it at some point.

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Thanks Trevor.

Did all V8's have the bleed screw on the radiator? I can see the one back at the engine, but I'm having trouble locating the one up front.

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mine is standdard, its on the top od the radiator on the left hand side. Look under the wheel arch and you should see the end of the radiator and on to there is a piece of sponge to make sure the radiator rots out. It may be under there. It looks like a bolt with a 10mm hex.

Trevor.


I'll get around to it at some point.

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Found it! Thanks.

I assume that when I open the bleed screws, coolant is going to run all over the engine and floor. Is there a technique that you use to prevent this? I'm one of those that try to keep the car (and garage spotless). :ermm:

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radiator: open the engine bay and get an assistant (this is an ideal time to make the wife share the pain, or a crafty way to introduce yourself to a neighbour). Undo the bleed bolt in the rad and then get ready to replace it. Ask the assistant to remove the expansion tank cap. Air will escape from the bleed hole and then some burbling coolant and air (about 2 to 3 seconds) and then as soon as the burble stops, replace the bolt. You should lose less than 100ml of coolant and so putting an old towel around the rad and suspension should keep everything shiny clean. Also wear gloves because cooland is horrible sticky crap when it dries on your hands. Same goes for the engine bleed (only without the assistant. Use the towel again and then unscrew the grub scew. (Note that it is a weird imperial size: 3/8 inch I think) If you get coolant coming out with the expansion cap off, put the screw back. If not, addit a little at a time and the put the screw back as soon as you get coolant. Repeat this procedure in 100 miles. You should spill hardly any. I would have the heater on full hot when bleeding. My bleed screw is stuck fast so I do this by lifting the top of the hose with a small pry bar but the effect is the same. Manual and parts manual can be found on e-bay on CD ROM for next to nothing by the way.

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a more simple way is (and often helps as much as the other..) lift your car up on the rear, fill with coolant in the main tank, and also fill the 'expansion overflow' tank next to the RH rear-wheel (outside of the enginebay). If the car/engine runs (with heater on full!) the water flows all around and air gets transported to the highest points -as soon as the heat is on the temperatures (on idling) that the fans kick in the water expand will also overflow in the pre-filled expansion tank in the wheelhouse. Use a bottle there on the pipe to collect any freshly mixed cooland (so all stays clean on your garage floor) ..and let the car cool down. The level in the main expansion tank inside the engine bay should now be *on full*, and stay there for the next drive cycles. If not there is still some air in.

-the trick is: if you just fill in (in cold condition, prior to bleeding or heat up) cooland into the main expansion tank, it will look like it is full up to the *max*-level -but you have air in the system (as this is your problem as we see..) -if you now start the engine the remained water will expand and flow into the outside overrflow/expansion tank, and the air that was inside your system will (with a bit luck) pass by itself outside to the atmoshere, but you will still have less water in your cooling system than it was meant to have. So prefill the expansion tank outside in the wheelhousing first, as any water that is to much will get into your old softdrink-bottle (for later resuse/refill you can store this in the trunk) and the engine can regulate the fluid-levels byitself. Other positive point is -you don't need tools to undo the (sometimes) sized bleed screws -so no risc of damage on the radiator or aluminium pipe..


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to name the things if I see them, that's what I call integrity..

*********************************************************************

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I hate jacking the back of mine as the gearbox input shaft has a slight leak which gets much worse if I jack the back up!

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Thanks John & Gunter. Great advice from both of you.

It's difficult to tell if I'm getting much air our of either of the bleed screws (plenty of coolant escapes). I've bled the system 3 or 4 times now and it seems to have made a small difference. My temp gauge still aproaches 120 degrees sometimes and I can hear the fans running, but they don't seem to cause the temp to drop as quick as I would think it should. If I turn on the heater it has a dramatic effect at lowering the temp gauge. I'm beginning to wonder if perhaps it's not an issue with air in the system, but rather a blockage in the radiator? The radiator fins are clear of debris.

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or a sticky thermostat.....or a busted temperature sender....or a busted guage....or a busted wire.....can you tell I have had my car for over 10 years and nearly EVERYTHING has conked out at one time or another !!

It should not get to 120. I have only seen this when the thermostat has failed to open. When you see 120 on the guage, what is your coolant level light doing? On my car ('97), if the coolant level light is flashing, it means that the engine oil is overheating and you are seconds away from a disturbing (but hilarious) catastrophic discharge of half your coolant volume out of the right rear wheelarch. (Yes, this has happened to me as well, it's a good job I love this car). When you see 120, what is the car doing? If you take it for a run at 70 and then park but leave the engine running, the temp will rise and then fall when the fans come on. If the temp simply carries on rising, then the radiator is not functioning and the most likely cause would be a stuck thermostat. The temp should wander between 80 and 100 or so.

I would change the temp sender for the guage (I have done this every 2 years for the last 8 years). This is found by lying on top of the engine and looking down into the space between the thermostat housing and cylinder number five (frontmost left). There are two sensors side by side. One is large and looks robust (the ECU feed) and the other is a small crappy little thing. The small one is the one you want. pulling the wire off is easy and then simply remove and replace the sensor (no coolant will spill to speak of). The sensor is tightened with care (do not cross thread it and only tighten it until it feels slightly more than secure....the thread is conical and so easily crossed and never reaches a stop point, so crossing or shearing the damn thing would both be very expensive mistakes)

Getting the wire back on is another matter...Do you have any medical friends? You need a pair of sponge forceps. These are like a huge skinny pair of pliers with duckbill shaped ends and make holding the connector very easy. You can probably buy them on the net as disposable items for a few bucks.

If you replace the thermostat and the guage sender and you still see 120 with a flashing coolant light, the radiator would be the next target. What does your coolant look like? Is it as clear as a mountain stream or full of rusty, gunky crap? Unless recently changed, if it is clear, then blockage would be less likely. If you see 120 but with no flashing coolant level light, then the guage may be faulty.

One other thing.....For safety, I would put your air con on full at all times as this forces the ECU to run the rad fans all the time and will do no harm but may reduce the risk of the wheelarch nightmare.

Oh I could go on for hours...Change the thermostat and temp guage sender and get back to us. Hope this helps

BTW, I have always considered the heater in a mid engined car as more of an auxillary engine cooler !!

Edited by toyroom

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John

Touch wood I have no problems with my cooling on the V8. I do think your response is the reason I look am a member of the forum!

First class information put over in a very readable way and I just know that if(or is it when!) I have problems I am already much more ready to deal with it.

You just dont get this sort of info from a workshop manual.

Thanks

Mark

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I've just read the beginning of this thread again. (That'll teach me) Was the car without these problems prior to the thermostat re-fit? If so, the adage is that the fault is nearly always due to something you have done. Ten bucks says the new thermostat is faulty. Occam's Razor strikes again!

Replace the thermostat again and check the removed one for vertical scratches on the central bit. This would indicate sticking.

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information about the location of the temp.sender unit is in the workshop-book as well ..and the 'medical' thing ..isn't that what we love those cars for ! :D

notice: even if the radiator looks 'clean' -what you only can see is the front of the aircon-radiator, and some areas of the main water radiator from the back (if you look under the front of the car..) -the critical point is how it looks like between this aircon- & main-radiator !! ..my unit looked clean as well, but only from outside, as soon as I have undone the whole unit and taken apart everyting an unique 'Biotop' full with undiscovered creatures was seen

..for flushing of the radiator itself it helps to mix up some natural acids. Just drain your whole cooling liquid, store it for later reuse ..and fill in some gallons/Liter winegear or other natural acids and water. Run the engine for a full warm-up cycle, drain all conted out and flush with clear water from a garden hose for several minutes (with all bleedings open)


*********************************************************************

to name the things if I see them, that's what I call integrity..

*********************************************************************

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Mark said it best. You can't find this sort of information in a workshop manual (I have my own copy now, by the way). The community here on TLF have got to be the most helpful people that I've met.

I agree that a fault can usually be found near the last thing one has touched. However in this case, the fault occurred before I did anything.

To start at the beginning, I was out for a casual drive (city driving, nothing spirited) when I noticed the temp lamp light (then flash). The guage was at 120 and I quickly pulled over and let the car cool down. I made it back home by turning up the heater (aka auxillary engine cooler, lol)

Once home, I checked the coolant level and it seemed fine. The overflow tank in the wheelwell only had about 1/2 an inch of fluid though. The coolant looks clean. I suspected the thermostat was faulty, so I replaced it. (I tested the new on AND the old one with boiling water from the wife's kettle and they BOTH opened fine). I saw the temp sender units while I was laying on top of the engine.

I looked for debris in the radiator (underside of the car where the fans are, and from the front through the screen). No build up of anything that I could see. I suspected that perhaps I had air in the system, so bled it several times. I THINK that I got the air out.

I did try running the aircon and the radiator fans DO run, but it doesn't seem to drop the coolant temp very quickly. Running the heater helps dramatically. The temp runs between 80 and 110 when the heater is on. If there was air in the system would the heater be producing heat?

I didn't realize that there were two radiators up front. Maybe there is junk between the two. My next steps (in order of least amount of work involved) might be to flush the system (it probably wouldn't hurt to do this anyways). Followed by removing the radiator. I do have an air horn that I've been meaning to install, so I could kill two birds with one stone there.

Thanks for the tip about the vinegar when flushing. I've read that running water backward through the radiator helps to get the bits out too. I'll have to find some hose fittings so that I can attach the garden hose.

Oh, any idea how many gallons / litres of coolant is in the system? I may need several large buckets to hold it all I'm guessing.

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.. (I have my own copy now, by the way). The community here on TLF have got to be the most helpful people that I've met.

..we do our best, as you see ;)

oh, this also locked good from font & rear ..but what I found between wasn't that good :D

168410_166474726731717_3257643_n.jpg

..water capacity is in the workshop-book, by the way *around page 388 in the PDF it is comming up with the Esprit-V8 data


*********************************************************************

to name the things if I see them, that's what I call integrity..

*********************************************************************

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As Gunter's picture indicates, sounds like clogged fins - or blockages in the radiator. Clogging tends not be visible in the sides of the radiator and condenser that can be seen.

You can try blowing with compressed air in the reverse direction to incoming air (required at each service interval).

Many of us have had this issue and usually, replaced the radiator with either a new one or a re-core. It's not the easiest of jobs . . .

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A minor point...there aren't 2 radiators, one is the air con condenser....Whatever you do, don't mess with it without getting the system de gassed. ALso, don't connect the garden hose direct, these radiators (especially the heater rad) are only built to take so much pressure.

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John, I'm not sure what kind of garden hose you have ..but we can regulate the water amount on the tap ;)

that's why I say with all bleeding points open (and for sure one end of the whole system of hoses under the front of the cars not attached ..so it is open and wouldn't build up any massive pressure)


*********************************************************************

to name the things if I see them, that's what I call integrity..

*********************************************************************

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So what happened in the end? I read through these stories, and the end is rarely included... At least it hasn't been 4 years since the last post, but you must have found the problem after 6 weeks.

Mark said it best. You can't find this sort of information in a workshop manual (I have my own copy now, by the way). The community here on TLF have got to be the most helpful people that I've met.

I agree that a fault can usually be found near the last thing one has touched. However in this case, the fault occurred before I did anything.

To start at the beginning, I was out for a casual drive (city driving, nothing spirited) when I noticed the temp lamp light (then flash). The guage was at 120 and I quickly pulled over and let the car cool down. I made it back home by turning up the heater (aka auxillary engine cooler, lol)

Once home, I checked the coolant level and it seemed fine. The overflow tank in the wheelwell only had about 1/2 an inch of fluid though. The coolant looks clean. I suspected the thermostat was faulty, so I replaced it. (I tested the new on AND the old one with boiling water from the wife's kettle and they BOTH opened fine). I saw the temp sender units while I was laying on top of the engine.

I looked for debris in the radiator (underside of the car where the fans are, and from the front through the screen). No build up of anything that I could see. I suspected that perhaps I had air in the system, so bled it several times. I THINK that I got the air out.

I did try running the aircon and the radiator fans DO run, but it doesn't seem to drop the coolant temp very quickly. Running the heater helps dramatically. The temp runs between 80 and 110 when the heater is on. If there was air in the system would the heater be producing heat?

I didn't realize that there were two radiators up front. Maybe there is junk between the two. My next steps (in order of least amount of work involved) might be to flush the system (it probably wouldn't hurt to do this anyways). Followed by removing the radiator. I do have an air horn that I've been meaning to install, so I could kill two birds with one stone there.

Thanks for the tip about the vinegar when flushing. I've read that running water backward through the radiator helps to get the bits out too. I'll have to find some hose fittings so that I can attach the garden hose.

Oh, any idea how many gallons / litres of coolant is in the system? I may need several large buckets to hold it all I'm guessing.

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Sorry for the delay, sometimes life just gets busy and time has a way of slipping by. To make a long story short, the problem seems to be solved. (Knock on wood).

I flushed the system. Then filled with a 50/50 vinegar/water mix and ran until the temp was up (approx 110c). I let things cool down a bit then drained. Flushed 4 more times with water only, each time letting it run until the temp was up. All sorts of rust flakes and crud came out (maybe a teaspoon of rust - is this a lot?). I then added fresh anti-freeze and bled the system. This whole exercise seemed to help somewhat, but eventually the temp gauge crept back up dangerously close to the top of the scale.

I ended up taking the car to a local mechanic that specializes in (and owns) Lotus to check out the radiator. It turns out that the tubes were pretty restricted, so the radiator was replaced.

I've had my baby back for 6 days now and the temperature gauge hasn't once gone above the half way point (90c). Everything seems to be running smoothly once again. :)

Now... I just need to replace the GM horn with a proper air horn before I reinstall all of the trim and close everything up under the front.

Thanks again for everyone's help. If anything, this has been a great education and if (or should I say 'when') someone else finds themselves in this situation, then hopefully I will be able to contribute to helping them.

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if you use this in a higher concentration, and let it stay there in the warmed up water system even the old radiator could come 'free' a litle more .. winegear is good, but needs to be even more 'high concentrated'

..it's available even in big-pack , so you can have more than one cooling system cleaned up (and of course you can use it in your home for cleaning in the toilet after all) http://www.amazon.com/Foods-Citric-Powder-Ounce-Bottle/dp/B001E5E1IW

Also helps on all sorts of rusted steel, on recondition projects ..trust me, I'm known to be skilled in this over here :D


*********************************************************************

to name the things if I see them, that's what I call integrity..

*********************************************************************

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