Potential head gasket failure

[Jayw13702]

So my intergalactic IS300h looks to be faltering a bit.

we appear to be losing about 500ml of coolant over about 250/300 miles, fuel consumption is down to late 30’s (fill up to fill up) and performance is a bit lacking.

going to do a sniff test on the engine this week but wondered if anyone had any experience of doing a head gasket on one of these engines? Are there any pitfalls/quirks?

if it is the HG then I can’t complain, this will be the first time this engine has ever been opened up since it was built, and it’s now done 245,000 miles 

[PRT68]

Assume you've checked the oil quality, and for mayonnaise under the oil cap?

From your past exploits, I'm sure you'll get it sorted quickly.

As a former private hire driver, I know how it feels. Not earning, whilst having to spend out. 

Good luck!

 

[Jayw13702]

24 minutes ago, PRT68 said:

Assume you've checked the oil quality, and for mayonnaise under the oil cap?

From your past exploits, I'm sure you'll get it sorted quickly.

As a former private hire driver, I know how it feels. Not earning, whilst having to spend out. 

Good luck!

 

No mayo, just water loss and no apparent leaks either.

going to do a sniff test today to see if it is the case and take it from there 

it is a pain when something like this happens, I’ve had 4 trouble free, high mileage years so can’t complain

[PRT68]

Hope you find the problem. 

My highest mileage on one of my vehicles was 452,000! 1.8 Cavalier petrol. Bought at 100,000 and double manned 7 days/nights per week. Only consumables, and no head gasket fortunately. 

[Kermitpwee]

Have you replaced the original Water pump yet? It is very common on the is300h, mine was leaking even though i couldn't see it, replaced it on advice and it solved the problem, that wouldn't explain your mpg however

[Jayw13702]

Well it’s not the head gasket, tests have proved that’s still good.

the water pump was replaced about 50k ago and is still dry do it’s a bit of a mystery as to why there was coolant loss.

we’ve put the lower fuel consumption down to the colder weather and E10 as well as changing the wheel size to 17’s. Now that’s it’s warmed up a bit the mpg has gone back to mid 40’s 

[Mikey B]

E10 has had an impact on my consumption - 48-50 before, but now more like 44-46.

[Kermitpwee]

16 hours ago, Jayw13702 said:

Well it’s not the head gasket, tests have proved that’s still good.

the water pump was replaced about 50k ago and is still dry do it’s a bit of a mystery as to why there was coolant loss.

we’ve put the lower fuel consumption down to the colder weather and E10 as well as changing the wheel size to 17’s. Now that’s it’s warmed up a bit the mpg has gone back to mid 40’s 

Glad to hear all is good with the headgasket, I'm hoping to run mine to 400k miles, 101k at the moment, i have no problem replacing the hybrid Battery when the time comes, hoping the rest will stand up to it, 2017 plate, hoping for another 10 years. Here is wishful thinking!!

Do you service earlier than the 10k?

[PRT68]

Well that's a bit of a mystery. I once had similar, and it turned out to be a pin prick size hole in a hose, and only leaked out when hot and under pressure. Only other thing could be the heater matrix. Any damp carpets?

[wookee]

Hey Jason,

To be clear - is it inverter coolant or engine coolant that you're losing? I'm assuming engine, since you mention the head gasket.

Re the MPG drop, I'm guessing that this started around the same as the coolant drop? On the premise it could be  coincidental, have you inspected / replaced your spark plugs and coils lately? I think sparks are due every 60k, so they would have been due on yours at 240k. When I replaced mine at 120k, I found oil in the wells of some of the plugs. After cleaning out and replacing with new Denso plugs, my MPG went back up above 50. A few of the plugs I replaced were not torqued down to spec (pretty loose), so perhaps that's how the oil got in there. Tube seals appeared fine otherwise, and tips looked healthy. Hey ho.

Hope you figure it out!

PS. Thanks for all your excellent write ups. A huge help! Hoping to do my transmission fluid this weekend.