G-car Coolant problem - LotusTalk - The Lotus Cars Community
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post #1 of 19 (permalink) Old 05-24-2019, 07:27 PM Thread Starter
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G-car Coolant problem

Hello Brain Trust, give me your thoughts on this.

My '85 Turbo Esprit is spitting out coolant, and I'm not sure why. I added a pressurized header tank and a recovery tank, but every time I run the car the full header tank empties maybe halfway, seemingly through the recovery tank, but does not draw the coolant back from the tank. I've tried different header tank caps, and the coolant in the recovery tank flows back to the tank if I raise the recovery tank above the (open) header, so that hose is clear, and does not seem to be collapsing with suction. The recovery tank is down by the battery, hopefully not to low to function as I think Lotus put it there on later cars.

I filled the car on a pretty good nose down slant, and ran it for a bit to try to circulate out any trapped air, allowing the coolant to warm enough for the thermostat to open. I puzzled by it's behavior- With a funnel sealed to the header tank fill, the car at idle will fill the funnel partway (~24oz?) as the car warms up at idle, and the tank contents are pulsing with the flow. The strange part is when I rev the engine a bit, it sucks the coolant back down out of the funnel, and when I let off it rushes back into the funnel. after the engine is off and it starts to cool it SLOWly draws the coolant out of the funnel and back into the header tank.

I wonder if I have a slug of air that expanding when heated and forcing out the coolant. My car does not have the radiator bleed in the top of the radiator, so I'm contemplating raising the right front corner as high as possible and loosening the upper radiator hose to try to get some trapped air out that way. I'm kicking myself for not adding a bleed fitting when I had the radiator out. I've since raised the header tank 45mm to ensure all the air can bleed from the J pipe, but doubt it will help.

I considered a blown head gasket, and have a block checking kit on hand, but can't use it yet as the coolant level rising in the tank leaves no air to draw through the checker fluid.

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1985 BRG Turbo Esprit
Chargecooled w/Megasquirt EFI
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post #2 of 19 (permalink) Old 05-24-2019, 09:41 PM
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I had similar issue when my 87 Esprit arrived in 2016.

I have the OEM expansion tank and the cap was problematic.

Eventually i got what I believe was the correct cap (JAE), but with the 'wrong' cap (don't know how the previous owner dealt with it) the expansion tank drained every other tank of gas.

I had an overflow container installed but it too initially didn't work. The new cap was leaking and it took some fine grit sand paper to make the metal-to-metal seal stop leaking.
There was a rubber gasket initially but simply seemed to be wrong.

You have a custom aluminum tank so not sure how you debug the cap on that one.

My bet is the cap sealing is the issue.

Eddie B
87 Esprit 'SLEEK GT'
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post #3 of 19 (permalink) Old 05-24-2019, 09:43 PM
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If you had a blown head gasket you would be eating coolant and if the system is otherwise patent you would see the level of the header tank go down with no visible leakage. A very quick check is to pull the plugs. If one or more look perfectly clean, and looking into the cylinders if it appears that the piston(s) are clean and shiney that indicates a head gasket leak. You can also pressurize the coolant system if you have the tool. If the gasket is blown you won't be able to hold pressure and you will see fluid flow into the combustion chamber. The exhaust gas detecting kit will be definitive and is the quickest and easiest way to check.

If it's an air issue and you can't get the air out any other way try using an Airlift filling tool. It will require you to drain and refill the system but it will definitely end problems with trapped air.

Tom Mieczkowski
1989 Esprit Turbo
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post #4 of 19 (permalink) Old 05-25-2019, 02:49 AM
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caps n stuff

I ever tell you I hate the coolant system on this car,, especially the coolant recovery tank. I also bought a JAE cap and the seal and fit is caveman at best engineering job. I sanded bought two other caps and did the sanding the face surfaces..... The tank is always half empty half full depending on your personal preference. I had my tanks re-core and they filled in the upper bleeder. I drove the car hard up and down mountains here and left the heater valve open to get the air out. I gave up on trying to do a closed system and now just keep and eye on the overflow tank. These days it pretty much stays at the half full position. I leave coolant in the front bonnet on long trips as a fail safe. I also worried about a head gasket leak or a cracked head letting combustion gas back in the coolant. I took a 907 engine out of my sons Jensen Healey and the head was off by the previous owner. There was excessive erosion of the block between 2nd and 3rd cylinder area. Looks like the coolant was not right. A coolant with aluminum package is critical as is good grounds. The inside of the water jacket areas was full of a rust looking oxidation. The owner was just adding water it appears. Look around the head gasket area and make sure you are okay there. Good luck you are dealing with Hethel brew pub engineering.
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post #5 of 19 (permalink) Old 05-25-2019, 04:12 AM
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I second sleekgt's idea that poor sealing of the header cap is allowing air to re-enter the cooling system. This experience is from other makes of car, so it is not just a Lotus thing.

First, assure that there is a rubber gasket around the TOP of the pressure cap on the header tank. (Later Lotus caps did not come with this seal, who knows why? #$*%$&
I ended up buying a dusty 15-lb Stant cap from my local autoparts store that had both seals) Also make sure that the cap's lower spring-loaded seal contacts its mating surface on the header tank.

As Jenna mentioned, make sure that the mating surfaces are smooth, no gouges.


Junctions or fittings in the hoses from the header to the recovery tank could allow air to be sucked in as the engine cools. (What are the hoses at the base of the funnel in your second picture? And where did you mount your recovery tank??? )


+++++++++++++

Regards the need to bleed the rad: Our Esprit's bleeder has been inop for years. Some spirited driving at high RPMs has been enough to purge any air from the cooling system. (Hey it's a tough job, but I don't mind doing it, LOL)
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'88 Esprit
Succasunna, NJ USA


"Not all angels have wings." - Turbo R
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post #6 of 19 (permalink) Old 05-25-2019, 07:20 AM
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A definitive test is to test for products of combustion in the coolant. You can get the kit at any large auto store. Once you confirm that you have a combustion leak the only fix is to pull the head. Most often happens because at some point in the past the motor was overheated.

Last edited by sleekgt; 05-25-2019 at 09:38 PM.
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post #7 of 19 (permalink) Old 05-25-2019, 09:43 AM Thread Starter
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Thanks for the input everyone

The aftermarket header tank has a normal double rubber seal type cap with the overflow nipple between them. I've run three different new caps so far, and they seem to have normal resistance when they go on, and impressions on the seals when they come off. Maybe I'll try drawing a vacuum on the recovery tank nipple and see if I can hear a leak.

I did a pressure test when this first went together, and it held fine, but that doesn't test the cap, and I should do another anyway to see if anything has changed.

Plugs look evenly colored, without the greenish tinge my last head leak gave them.

The car seems to cool just fine, I'm just worried the level in the tank will continue to drop and then I will have a head gasket issue for sure! Also mystified as to where the coolant goes when I rev the motor.

1985 BRG Turbo Esprit
Chargecooled w/Megasquirt EFI

Last edited by snowrx; 05-25-2019 at 10:28 AM.
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post #8 of 19 (permalink) Old 05-25-2019, 02:13 PM
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Don't panic until you do 5 or 6 drives, that is the number of drive cycles it takes for coolant to purge and the level to stabilize.

If you want to be proactive, you could test for leaks again. If you have a non-pressurized recovery tank, you would need to clamp off the hose to it. You can borrow a cap tester from most auto parts stores, too (but three bad ones, unless the all don't quite fit', tells me they are working as designed)


WHERE is the recovery tank, again? And tell us about those hoses in your second picture, above.

Atwell Haines
'88 Esprit
Succasunna, NJ USA


"Not all angels have wings." - Turbo R
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post #9 of 19 (permalink) Old 05-25-2019, 02:20 PM Thread Starter
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Pressure tester holds 1 bar for 90 minutes, I think I'm OK there (at least with a cold engine!)

Carbuff, here's my recovery tank location. Header, chargecooler and overflow hoses
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post #10 of 19 (permalink) Old 05-25-2019, 02:30 PM
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Did you open the bleeder screw on the radiator? With the nose down, you can capture air at the radiator. There should be a small cover over a bleed screw by the drivers side headlamp inside the front compartment.

Mike

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post #11 of 19 (permalink) Old 05-25-2019, 03:14 PM
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Quote:
Originally Posted by mike.griese View Post
Did you open the bleeder screw on the radiator?
See post 1; doesn't have one.

Atwell Haines
'88 Esprit
Succasunna, NJ USA


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post #12 of 19 (permalink) Old 05-25-2019, 03:17 PM Thread Starter
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I've got the cover, but nothing under it-

Anyone know if that circular plug in the end tank is thick enough to tap some threads in? Or have a photo of the OEM bleeder?
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post #13 of 19 (permalink) Old 05-25-2019, 09:38 PM
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Quote:
Originally Posted by jtrealty View Post
A definitive test is to test for products of combustion in the coolant. You can get the kit at any large auto store. Once you confirm that you have a combustion leak the only fix is to pull the head. Most often happens because at some point in the past the motor was overheated.

The mechanics tested for combustion products in the coolant during the debug phase - zero.

That's why we went through the various caps and sanding of the mating surfaces, etc.

Suprised that this was an issue on my 87 - had zero issue with this on my late 88.

Eddie B
87 Esprit 'SLEEK GT'
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post #14 of 19 (permalink) Old 05-26-2019, 05:49 AM
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My cars have a tapped bung on the side and corner opposite of the hose connection - remember the radiator is laying down a bit so the vent would have to be on the forward surface. A drain plug fitting would work just as well.

Mike

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post #15 of 19 (permalink) Old 05-26-2019, 11:32 AM
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Did the late G Turbos have overflow tanks originally? My '86, which I believe to be original, just has an overflow hose that dumps on the ground. My expansion/header tank is normally about 2/3 full and stays that way so I'm not sure you really need the overflow reservoir.
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post #16 of 19 (permalink) Old 05-26-2019, 12:26 PM Thread Starter
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Quote:
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Did the late G Turbos have overflow tanks originally?
After my car overheated once I wanted to add a larger tank + recovery so I had more coolant in reserve. That and I've not had another modern car that did not come so equipped, so figured the OEM's must be spending the money for some good reason. And I can never leave good enough alone.....

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post #17 of 19 (permalink) Old 05-26-2019, 12:32 PM Thread Starter
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Quote:
Originally Posted by mike.griese View Post
remember the radiator is laying down a bit so the vent would have to be on the forward surface.
The untapped circle in my photos is accessible from the wheel well on my car, so if it's thick enough to take a thread I might use it (someday) but don't think I can tap it in place.

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post #18 of 19 (permalink) Old 05-26-2019, 03:26 PM
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Originally Posted by 2Many Cars View Post
My '86, which I believe to be original, just has an overflow hose that dumps on the ground.
Just make sure that the hose points AWAY from the RH disc brake.

Just sayin'.


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post #19 of 19 (permalink) Old 05-26-2019, 09:33 PM
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Quote:
Originally Posted by carbuff View Post
Just make sure that the hose points AWAY from the RH disc brake.

Just sayin'.

Yup. I noted that and rerouted the hose. Thanks for the warning.
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