220d Coolant overflow when revving

samanaslt · April 18, 2019

Hello, I have an issue with my IS 220D, 08 plates, 117k miles.

I bought car November 2018, only problem I noticed is that coolant is leaking through overflow pipe on coolant reservoir tank.

Higher revs on engine, higher coolant goes in coolant tank till it overflows. And just usually spills out till it just below low line.

After reading these forums back in December, I went to do head gasket test.

Test came clear and they just recommended me to change cap.

Bought brand new genuine cap from dealer, problem still exists.

I've been driving car everyday since November around 5k miles, coolant temp always just bellow middle, never attempted to overheat, no smoke, no mayo on cap, no warnings on dash.

It never been issue except that it splashed coolant all over engine bay.

Can somebody please explain to me what's happening, because local garages have no clue.

Thank you.

Shaunomercy · April 18, 2019

You are I suspect getting compression going into the water jacket. Hence it pressurising and losing coolant.

The easiest way to test is hold the water pipes that go into the rad. If you can feel pulses then compression is getting into the water jacket .

You might not get an oily ring around radiator cap or immusified oil.

ColinBarber · April 18, 2019

Almost certainly the head gasket I'm afraid. Get the engine pressure tested (again) to confirm.

A stuck thermostat could cause this issue, or trapped air in the cooling system which expands when hot and pushes out the coolant, but these are both very unlikely given known issues with this engine and loss of coolant through the expansion overflow being one of the clear signals.

samanaslt · April 23, 2019

On 4/18/2019 at 9:22 PM, ColinBarber said:

Almost certainly the head gasket I'm afraid. Get the engine pressure tested (again) to confirm.

A stuck thermostat could cause this issue, or trapped air in the cooling system which expands when hot and pushes out the coolant, but these are both very unlikely given known issues with this engine and loss of coolant through the expansion overflow being one of the clear signals.

Yeah, but if that would be a head gasket, would it not being showing any other symptoms in those 6 months I've been driving?

Also sometimes I can hear some bubbling sound behind dash when starting car, but after opening coolant bottle cap sound disappears for a week, and then it reappears.

ColinBarber · April 23, 2019

seems very similar to this:

steve2006 · April 23, 2019

Ask your local MOT tester to sniff the air in the coolant reservoir with the emissions probe, if it detects exhaust gases this would confirm head gasket issues. You could also have a cylinder pressure test performed where high pressure air in then look for bubbles in the reservoir.

samanaslt · April 25, 2019

On 4/23/2019 at 7:58 PM, steve2006 said:

Ask your local MOT tester to sniff the air in the coolant reservoir with the emissions probe, if it detects exhaust gases this would confirm head gasket issues. You could also have a cylinder pressure test performed where high pressure air in then look for bubbles in the reservoir.

Done chem test on coolant reservoir, yes fluid changed colour to green. Exhaust gasses getting in somewhere into cooling system. Can it be EGR cooler or anything else. Or only answer is HG? How to know for sure?

steve2006 · April 25, 2019

Given the HG is a known problem with this engine the chances are it will be the gasket. Lexus extended the warranty some years ago due to the many problems with the diesel engines used, many vehicles ended up with virtually a new engine!

samanaslt · April 26, 2019

12 hours ago, steve2006 said:

Given the HG is a known problem with this engine the chances are it will be the gasket. Lexus extended the warranty some years ago due to the many problems with the diesel engines used, many vehicles ended up with virtually a new engine!

Could some sort of HG sealant help out on 220d with situation I have? Perhaps it's a small leak?

steve2006 · April 27, 2019

I guess you could try it for what it costs but it wouldn’t provide a long term fix. IIRC the main reason for HG failure was due to the gasket moving between the block and cylinder head.