Speedy0o

Hi all, yet another issue I seem to be having with my 450h. Noticed yesterday on a local run to the shops that the heating was taking a while to get warm, as its usually pretty quick to heat up!
Had a play around today and noticed that the heat from the vents went cooler when slowing down and the engine cuts off(battery mode), then if I give it some stick and the engine cuts in again, the heat comes back! After a while of driving though it seems to stay warm all the time!

Kind of suspecting inverter cooling water-pump could be about to die on me, but I'm getting no error codes or lights on the dash! Anyone else think of another reason this could be happening?

Speedy0o

Can know one shed some light on this or has anyone had similar issues? Don't tell me I'm being the guinea pig for the GSh community! Hate it when that happens!! Think I'll ignore it for now and hope it goes away lol!

Seems to be that it I keep the engine running it warms up and blows warm but as soon as the engine stops at a junction or under 40mph it goes pretty cold! Then warms up once you rev he engine again!
Could there be some sort of valve somewhere in the coolant system that isn't opening unless the pressure behind it forces it to open(engine water pump forcing the water through the valve) hence the reason it goes cold when the engine cuts out??

Cheers

Ben

rjk

A few things I am guessing, not having any experience with the Hybrid model.

1 - Stuck or frozen thermostat, resulting in sub-optimal coolant routing. This can also cause overheating of your engine, check your dash to see if it's running hot.
2 - More likely: Coolant pump is working fine, but coolant system is partially obstructed or blocked. Flush it.

How many miles are on your GS?

Speedy0o

Yea my first thought was the thermostat but the gauge doesn't move over half way or just over when at full temp, and when driving for long periods at speed it works fine and doesn't over heat at all!

What would be involved in flushing the system? Drain, refill and then drain, refill again? Adding this gumph into the coolant too perhaps??

http://www.roughtrax4x4.com/p/1934/f...FernwgodYw4AFQ

156k on the clock

rjk

I'd look back in your service history to make sure everything was done regularly. As for the coolant flush, any dealer should be able to do it, and I don't know whether an additive like you mentioned is necessary or not. I figure the hybrid cooling system shouldn't be too far different from the regular one, so anyone that's done a regular car should know what to expect. But I could be far off base on that.

killerkhan

Hey, speedyoo. I have the same problem with my 07. The problem has been there for more than a year. I went to the dealer and they couldn't figure it out. Did you have the problem fixed yet?? Thanks

Speedy0o

Just rechecked this thread as thought I had replied but obviously didn't hit send!
Anyways, no I haven't cured it yet but I'm going to try a coolant flush soon with an additive to help clean out any dirt/debris that might be causing a blockage! Can't say that's going to cure it but it's worth a try since it's the cheapest option I can try first! Typical it's failed on me as we're hitting the coldest part of the year over here!

Speedy0o

Just had a feel of the rad hoses and hoses that go into the matrix (engine side of bulk head) and matrix hoses feel warm (both of them), the top hose to the rad is warm but not hot and bottom hose is cold suggesting the stat hasn't opened yet. Its cold outside so getting the car up to temp is quite difficult without a long drive (rush hour at the mo).



Still I just had the car parked on the drive and cranked the heater up to max and held the accelorator for a while and super warm air blows out. The engine cuts back out as "normal operating temp" has beenreached for battery mode and then the heater goes cool again! Still the bottom radiator hose is cool and top hose not massively warm. It has never overheated thus far and I drive 150miles a day back and forth to Reading from Cheltenham 4 nights a week.



Only thing I can think of is a sticky thermostat or waterpump not operating sufficiently enough to circulate the water?!?



Anyone got any other ideas? Its getting colder and short trips where it used to blow warm air nice and quickly (within 3-5miles) are becomming unpleasant!

d6lc

Been driving my GS through the Minnesota winter, so starting and driving at -20C has been the norm.
Mine seems to warm up fine, and heats the cabin as good as our Merc V8, I notice that the engine temp guage drops when I stop at lights, but I would not say the heater blower temp drops in any way.

Speedy0o

Sounds like yours is fault free then lol, mines got an issue somewhere but without taking it apart to try and find the fault I'm pretty clueless as to what it could be! Pretty annoying, I'd almost want to say waterpump now though as after driving 75 miles yesterday and stopping for fuel for 5mins, the heating went cool again!
I'm not sure if there's a valve somewhere that controls water flow to the matrix or even if the matrix is blocked but its just so strange!

Speedy0o

Think I've found the source of the problem!! I Started the car up at work yesterday from cold and let it idle and come up to temp. Sure enough the temp gauge rises and still the heating doesnt get warm. Thought I'd double check the heater matrix hoses in the engine bay, 1 was scolding hot and the other stone cold (still blowing cold in car). So i hit the accelerator and waited for warm air to blow through, then quickly went round and felt the pipes. The cold pipe was now hot, I stayed round by the pipes and let the engine idle again for a while and the pipe eventually got cooler and the air in the cabin grew cooler with the pipe.

This suggests that the heater matrix is partially blocked and that when the engine is revved, the water pump turning faster is forcing coolant through it and making it hot! Hopefully I can fix it with the garden hosepipe by taking the two matrix pipes off under the bonnet and flushing it through backwards to dislodge the blockage!

It may have to wait until the weekend though!!!

sonnyhood

Hi guys, theres a simple solution to a complex problem.
When the motor is off the water is not pumping im guessing? Since it will be a belt driven water pump.
If you want the motor to stay on in those cold days you need the engine running.
Easy way just slap the gear in to S Gear and the engine wont turn of when it comes to a stop.
I use 4 when going 50-70km/h and 5 gear when going 80-90.
UNder 70km/h you can safely leave the gear in 4 and drive everywhere.

Edit: Also i read in the book its not good for the hybrid system to press the accelerator when parked or not moving.

Speedy0o

It has an auxiliary water pump driven electronically via the hybrid system, when the engine switches off the electronic pump takes over the engine water pump duties and continues circulating the coolant around the engine. If ur driving on battery mode the coolant will still be circulating and will still be warm so you will still have heat coming through the vents. The car monitors coolant temperature and when it drops it will automatically cut the engine back in to warm up the coolant!

Also if it blows cold when the engine is idling then it has nothing to do with no circulation unless the matrix is blocked, which has to be my problem!

Speedy0o

UPDATE

Pulled off the heater matrix hoses yesterday, (cutting my hand in the process ) I ran a hosepipe through the matrix, backwards first in an attempt to clear out any debris or blockages on the inlet side and it ran clear and straight through. Ran it through the correct way round and again no restriction or blockages and ran clear straight away.

I took the cap off of the thermostat housing (while cold) and noticed there was no coolant in it whatsoever. So I re-fitted the matrix hoses (really really easy to take off and run a garden hose through BTW) and started her up, it belched a small amount of coolant then immediately went dry again, so i topped it up (with water) till overflowing, put cap back on and squeezed the top rad pipe for 10secs or so, cautiously removed thermostat cap again to find it empty, so topped up and repeated hose squeezing until, when I opened the cap it decided it was gonna go everywhere (system full) to which i stopped!

My heating's been blowing hot ever since, so it must of been an air-lock in the coolant system causing a bubble of air to be trapped inside the heater matrix pipes which seem to be the highest point in the cooling system! So there you have it, hopefully if anyone else has this issue then this could be a fix for you

sonnyhood

thanks for that update.
i know i did my coolant service at 160,000kms at lexus, they drained 15litres or somerthing ridiculous of coolant which is shared with the hybrid system. air locks can be nasty.