Pressure In Hoses

[IanCornwall]

Hi everyone

Not sure if this is a problem but it does seem to be a bot of one

I toppped up the radiator and put the cap back on

After a few minutes the top hose is like concrete under pressure

The expansion tank doesnt seem to be connecting up to the overflow, I mean the pipes are there but nothing happens, water doesnt flow from the expansion tank to the rad or vice versa

How should the expansion tank work on the GS300 mk 1 ?

[IanCornwall]

hi everyone

shame no one seemed to know how it works, so I dived in this morning and sorted it out

if you read my other postings you may recall that the car had done very little miles between MOT for the past 4 years

I removed the air intake and disconected the first section of hose, all was clear, then went along the hose, there are 3 clip together sections and still all clear

then I removed the header tank and it was basically full of sediment, and with the car not moving much i reckon the sediment had settled into concrete

I used the bleach and oven cleaner method to remove the sediment and cleaned the hole out at the entry of the tank which was blocked solid

I connected it all back up, and now it all works fine, the hoses are under normal pressure now and the pressure can relieve itself into the header as it is meant to

I spoke to a Toyota/ Lexus specialist in USA I found on the net and he said that when a car uses Toyota / Lexus antifreeze it needs changing on services as it does pick up the rubbish in the system and when people or some dealers flush the radiator to refill they often forget to clean the header tank which is more than likely to be full of the proverbial cr*p and if its not cleaned it is frequent that pressure builds up and hoses start popping or worse the rad blows

hope this helps anyone else

[maneesh]

thanks for sharing that mate..useful for the future..

[BigRoj]

hi everyone

shame no one seemed to know how it works, so I dived in this morning and sorted it out

if you read my other postings you may recall that the car had done very little miles between MOT for the past 4 years

I removed the air intake and disconected the first section of hose, all was clear, then went along the hose, there are 3 clip together sections and still all clear

then I removed the header tank and it was basically full of sediment, and with the car not moving much i reckon the sediment had settled into concrete

I used the bleach and oven cleaner method to remove the sediment and cleaned the hole out at the entry of the tank which was blocked solid

I connected it all back up, and now it all works fine, the hoses are under normal pressure now and the pressure can relieve itself into the header as it is meant to

I spoke to a Toyota/ Lexus specialist in USA I found on the net and he said that when a car uses Toyota / Lexus antifreeze it needs changing on services as it does pick up the rubbish in the system and when people or some dealers flush the radiator to refill they often forget to clean the header tank which is more than likely to be full of the proverbial cr*p and if its not cleaned it is frequent that pressure builds up and hoses start popping or worse the rad blows

hope this helps anyone else

[BigRoj]

Hello, I will get the hang of this replying lark!

Reading IanCornwalls problem has highlighted a strange setup on my '97 GS. When the car is cold the top hose is squishy, not under pressure as you would expect, but within a minute of starting it starts getting firm.

This worried me a bit as in any other car it would indicate a head fault of some sort with exhaust gasses getting into the coolant. So I ran the car up to operating temperature with the rad cap off, removing excess coolant as it expanded, but there was no bubbling up, nothing unusual at all! The temperature doesn't rise above half way when on a good run, the level in the expansion tank rises when the engine is hot and falls when it cools down as normal, so the connecting pipe is not blocked.

BUT.... it is losing coolant, I have to top it up now and again but there is no visible leak which made me wonder about the head but as it's running almost perfectly with no sudden rises in temperature I am at a loss as to where this coolant may be going.

I had an LS with a similar problem a few years ago but that used to gurgle as well. That turned out to be the water pump in the end (£650 to repair-yes, I know I was ripped off)

Anybody else come across this?

[IanCornwall]

Hi Roj

Unfortunately with me it has turned out that it was my head gasket and the blocked header was just sort of part of it

Although because of this when the radiator cap wasnt releasing the pressure it blew the waterpump

so i had a new waterpump and they did the cam belt same time, cost £230 for the whole job at local Independent garage (Lexus quote for the job £840)

Now I am rebuilding the top of the engine with new head gasket etc, quite an easy mechanical job and almost done now, biggest problem is getting the damn vacuum hoses right

[BigRoj]

Hi Roj

Unfortunately with me it has turned out that it was my head gasket and the blocked header was just sort of part of it

Although because of this when the radiator cap wasnt releasing the pressure it blew the waterpump

so i had a new waterpump and they did the cam belt same time, cost £230 for the whole job at local Independent garage (Lexus quote for the job £840)

Now I am rebuilding the top of the engine with new head gasket etc, quite an easy mechanical job and almost done now, biggest problem is getting the damn vacuum hoses right

Hello Ian,

Not the time of year for doing head-gaskets if you're working outside! These 3 litre Lexus engines seem a bit delicate where the coolant is concerned, or so it seems when you read the posts that have been put up.

This is another problem with engines that have sophisticated management systems. If you have a problem of some sort the engine will still start simply because the ECU will either compensate for or over-ride it. Not like when you had a carb and points and the car wouldn't start if someone so much as farted near it, let alone anything else!

I shall have to keep a good eye on the coolant, check every day. I do need a new rad, and the cam belt will need doing soon, so I will do all that around the Christmas break, unless it all goes tits-up before then!

[IanCornwall]

Hi Roj

Even down here in the heatwave area of Cornwall, its getting cold outside. Today a small monkey came up to me while I was under the bonnet and asked to borrow my welding kit

I must say that once the control systems out of the way, the actual engine is a p.o.p. to work on, nice machining, quality nuts and bolts that don't wring the heads off, and almost sensible layout has made it easier to work on than the usual rubbish

Only 2 studs that are a pain in the proverbial to get to needed persuasion to sort out

When it is all finished I will post a guide to doing the head gasket