Expansion tank pressurising

[Psycho.]

Hi all,

I have an issue with coolant pressurising in the expansion tank located in the left hand side of the boot.

The PO replaced the chargecooler pump impeller, chargecooler/AC condenser, A/C condenser, A/C compressor and A/C belt just before I bought the car in November last year. When I drive the car 10 to 15 miles the water starts to pour out of the expansion tank overflow pipe under pressure. The temperature gauge reads normal so car is not overheating. Fans kick in when they’re supposed to. I have changed the CC tank cap as well as the expansion tank cap but problem still occurs.

When the car cools down, the coolant drops in the CC header tank and the expansion tank is almost dry.  There are no visible signs of any leaks in the pipework.

When driving it last night, I turned the heater control to hot and no hot air was coming out, not sure if this helps anyone in diagnosing problem. A/C is working fine.

The CC was really hot the first time it happened but last night the CC was warm when I switched engine off.

Could I have an airlock in the system?

The car had been standing for some time before I bought it and I was wondering if some of the cooling pipes could be full of crap.

I would welcome any suggestions from all you experts )

 

 

[CarBuff]

FIRST:  That plastic tank in the left side of the hatch is SUPPOSED to be pressurized.

 

It is common to get air pockets in the system after cooling system components are replaced. Check the (cold) header and pressurized overflow for the next 5 - 10 drive cycles.

 

Don't panic unless the coolant level continues to drop.

 

Some time at higher RPMs helps to purge air pockets, for sure. Its FUN, as well. 😁

 

++++++++

 

Watchpoints are a bad cap or rough mating surface on the overflow. (Some overflow bottles have a metal contact ring that rusts...preventing achieving proper pressure)

 

Cold fill should be at the 'waist' or center of the plastic reservoir tank. There should be a vinyl elbow & hose at the top to relieve excess coolant, if the coolant expands too much.

 

Regards chargecooler impellers:  If that system was inop for a long time, flow may be blocked. In this case, even a new impeller will not turn. 

 

Fit an electric CC pump (from a Prius), you will be better off.

Edited July 21, 2022 by CarBuff
Additional info

[Psycho.]

Thanks Atwell,

I did give it a blast at XXXmph down the motorway last night hoping it might clear any air, maybe I need to give it really dammed good thrashing 😁

When the car stops, the coolant does expand and pushes quite a lot of coolant out through the elbow and hose at the top of the expansion tank in the boot/trunk. This morning I cold filled the expansion tank to the fill line and the level has remained at that level all day.

The new expansion tank cap I got from SJ Sportscars has a rubber seal, the old one was a metal ring, I assume the rubber seal is better.

I think for peace of mind I need to flush the whole system out. Would you recommend using something like a radiator flushing fluid or just water? My only concern is, if there’s a load of crud in the pipes and the CC, will a water flush just move the crud around and block somewhere else? I was thinking of flushing it from the front where the pipes connect to the rad and from the rear where the pipes enter the CC.  Ideally, I’d like to remove the CC and clean that out but I’m not sure if you can use any strong chemicals to remove the crap from inside?

The car did sit from 2006 to 2012  and only did 50 to 100 miles a year after 2012. I don’t know if the PO drained the system when it was not being used. The header tanks have quite a lot of rust inside.

You are right, the way to go is electric CC pump, but as the PO replaced the impeller less than 100 miles ago, I thought I’d run this until winter then I’ll change it for an electric pump.

Edited July 21, 2022 by Bibs

[CarBuff]

The original 'green' coolant is prone to developing a crust throughout the system, for sure. There are several opinions about which coolant to use.

 

Whatever, it needs to be compatible with both the aluminum (aluminium 😇 ) engine components and the original brass radiators.

 

Some owners use a small bucket of CRL (a bathroom cleaner that removes Calcium, Lime, and Rust) and circulate it through the CC, heater matrix, and radiator with an electric drill pump. It is important to flush this stuff out, however! I'm sure there is a similar product on your side of the pond if you can't buy it through Amazon.

https://clrbrands.com/Products/CLR-Household/CLR-Calcium-Lime-and-Rust-Remover

 

+++++++

 

The test for CC effectiveness is to take the car on a 30 minute run. (Its not the speed, its the RPMs) Then immediately put your hand on top of the chargecooler.

If you yell OUCH and your hand burns, the system is plugged somewhere.🥶 If you can leave your hand on the CC for 10 - 20 seconds with only minor annoyance, the impeller IS working and the coolant is circulating. We have had chargecooler pipe that develop pinholes near the left front.

 

https://www.lotustalk.com/threads/chargecooler-pipe-leaking.253849/#post-3452001

 

Alternately, you can remove the largish fill plug and actually watch the coolant flow, but sometimes those cannot be removed easily (dissimilar metal syndrome).

 

Assume your 1990 car has separate CC and engine coolant header tanks?

[Psycho.]

The coolant that’s in there is red.

When I flush the system, I will use a red longlife antifreeze that is suitable for nonferrous metals. It’s supposed to clean and protects against corrosion, attacks and helps preserve the non-ferrous components in your engine. It contains 95% Mono Ethylene Glycol and 5% Corrosion Inhibitor.

I’m a bit worried about using something like CRL, most of those cleaners have acid in them that can attack the aluminium. I was considering having the chargecooler ultrasonically cleaned, maybe I’ll put another post up to get people’s views on this.

The first time the coolant came out of the expansion tank, I checked the chargecooler and it was an OUCH moment! However, the other night when it did it again it was only luke warm to the touch.

I removed the fill plug (yes it was tight) and the coolant started to pour out of the top. I did wonder at this stage whether a pipe could be blocked.  

Yes the car has separate CC and engine coolant tanks.

[jonwat]

I've used Holts Speedflush previously in an Esprit engine with good results & no harmful effects 

[Psycho.]

Thanks John,

I'll probably use what you suggested unless someone else comes along with something else.

[CarBuff]

6 hours ago, Psycho. said:

I’m a bit worried about using something like CRL, most of those cleaners have acid in them that can attack the aluminium.

This is true, which is why folks that use CLR need to flush it out of the system after they use it.  It HAS worked well on many makes of cars who encounter clogged heater matrices.

 

(On the Esprit, never shut the heater control all the way off...with the pointer at the 5 o'clock position you will get some coolant flow, but no heat on warm days.)

[AndyPG]

7 hours ago, Psycho. said:

The first time the coolant came out of the expansion tank, I checked the chargecooler and it was an OUCH moment! However, the other night when it did it again it was only luke warm to the touch.

Hi Kevin,

As Atwell clarified, the charge cooler circuit and the engine cooling system are separate and unrelated on your car.

If you pull over and your charge cooler feels hot, you have a separate issue with cc circulation. Mine only gets luke warm even on a hot day. The water level in the smaller cc header tank should always be about 1" below the filler. The actual charge cooler body should be full.

If your cabin heater is pumping out hot air and the hoses to the top and bottom of your main radiator are hot, it's fair to say your main cooling system is purged and should be performing in a settled manner.

When my engine is cold, the plastic expansion bottle about 1/4 full. When the engine is hot, the plastic expansion bottle is just over 1/2 full.

If your engine isn't over heating and continues to push water out of the expansion bottle with the afore mentioned points checked, there may be a possibility of a head gasket issue.

Andy.

 

[Psycho.]

Update on the problem….  When looking at the 2nd expansion tank in the boot (trunk 😉) I noticed coolant leaking from the bottom of the tank, initially I thought the tank had split.   I decided to remove and clean the tank out (loads of crud in bottom).

After cleaning and testing the tank, (fortunately no leak). I started to put it back and inspected the bottom hose to the tank and noticed it had a tiny split where the jubilee clip goes. I cut the pipe back and reconnected…..leak sorted

I did as Atwell suggested, some time at high rpm. The level in the expansion tank started to rise near the top, I shut the car down, left it for a while until level dropped back to the fill level.

I repeated the process, this time the level went up a little then back down to fill level when I switched off. I left for 45 minutes and the tank was empty. I filled it up to the fill level and repeated the high rev process again, but this time with the rear of the car jacked up, level rose again but not to the top, then dropped back to fill level when switched off.  45 mins later tank was empty.  Filled again to fill level and repeated rpm process, this time level in tank was more stable. Switched off and 45 minute later tank was almost empty again.

CC did get a little bit hot but nothing like it did before.

I’ll drive the car over the weekend and keep an eye on it, hopefully it was just air in the system. If it isn’t, then it’s chargecooler off for cleaning as well as a serious flush out of the whole system.

I really hope it’s not a head gasket problem, 😱 there’s no sign of any water in the oil. I really don’t know where the coolant is going, there’s no sign of any leaks

 

[CarBuff]

Here's hoping the issue is sorted.

 

FWIW, the aluminum coolant pipes can corrode a bit, leading to leakage as the engine is warming up. (The pressure builds, the coolant leaks, until the pipes warm up & expand)

 

Any evidence of coolant drips encourages a look-see. Try to tighten the clamps...but if you ever disassemble a hose/pipe, apply a non-hardening sealer like Hylomar Blue to fill in the nooks & crannies.

[snowrx]

@Pyscho- I hate to say it but the gradual loss of coolant you're seeing is what the beginning of the end of my last head gasket looked like. I kept thinking I was bleeding out air, or had overfilled, but a head gasket put an end to it. Maybe try a combustion gas check on your coolant?