Cracked 2.4 head - bubbles question.

wobbly

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Nov 27, 2010
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Ok, its not for me, its for a friend.......

If the head is cracked or gasket gone, he should have some tell-tale signs, one of which is bubbling in the reservoir - but how much bubbling exactly? Like blowing down a straw, or just an occasional bubble once every few minutes?

Theres no overheating on the gauge, no emulsified oil, but the reservoir needs topping up when the engine is cold - the water must be going somewhere, so I suggested a gasket problem - now every time he comes round we have to stare at his water reservoir whilst his car idles, there's not a lot to see, just an occasional bubble which I think may be the stat opening and closing.

So what should we see?

Pete
 

wobbly

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Nov 27, 2010
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Oh yes, forgot to say....

His rad cap is not original - its a 'Drive Joy', with 0,9 marked on it (which must be something to do with pressure.

I think this may be the cause of his concern, but wasnt sure of 0,9 was correct cap.

Pete
 

Roger Fairclough

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Dec 14, 2010
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If a head gaskets going to go, it will start with a very small hole, but just like the dams we used to build on the beach, once the water starts over the top, all hell lets loose. Searing hot gases at considerable pressure will quickly increase that little hole to something sizeable. It will take just a few minutes and the bubbling will be frothy, smelly and "oops we have a problem".

First change that cap. Then check the hose from rad. to overflow tank and don't forget the semi rigid plastic pipe inside the tank.

Roger
 

Jimbo4x4

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Mar 2, 2010
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Correct cap, iirc, is 1,1. I think this is pressure in bar btw. A common mod is to fit a rad cap from an MR2 which is rated to 1,3. This helps save loosing coolant on long hills etc.
 
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MartinNaylor

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May 13, 2010
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wobbly said:
Ok, its not for me, its for a friend.......

If the head is cracked or gasket gone, he should have some tell-tale signs, one of which is bubbling in the reservoir - but how much bubbling exactly? Like blowing down a straw, or just an occasional bubble once every few minutes?

Theres no overheating on the gauge, no emulsified oil, but the reservoir needs topping up when the engine is cold - the water must be going somewhere, so I suggested a gasket problem - now every time he comes round we have to stare at his water reservoir whilst his car idles, there's not a lot to see, just an occasional bubble which I think may be the stat opening and closing.

So what should we see?

Pete
When the engine warms, it will push the water out to the reservoir so it should fill up or you may get the odd bubble.
When it cools the water will get sucked back into the engine to keep the rad filled, expansion and contraction.
A good sign is if the bubbles increase with REVS then the chances are you have a cracked/head gasket problem.
My KZJ70 was missing the pipe in the resevoir which caused it to overheat, it took me a little while to figure out what was going on as it only do it after a couple of drives, the water was not getting sucked back into the engine when it cooled, leaving the rad a little low.
Try the easy things first, cap, water pump(check, good sign is water coming out from around the pump as it has an escape hole in a failure).
Does it actually overheat?
 

wobbly

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Nov 27, 2010
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I think that there being coolant in the tank when hot, but none when cold, is in fact normal operation as you say - the water getting sucked back in when the vacuum is created in the system.

I wish I'd kept my mouth shut to be honest, I cant see any signs of a head problem - we had to go out again this morning to check, stopping every couple of miles, not a bubble to be seen, no smells, nothing.

He's going to change the rad cap - will be interesting to see if going up to 1,1 gives an increase in temp on the dial - I suspect the change was made to make the engine run at a cooler temp.

His concern was poor performance ie slow, and it is slower than mine, but its done 120,000 miles whereas mines done 60,000 so its not like for like exactly.

I know this engine isnt overly powerful, but its also an old type of diesel, not the modern common rail type which gives petrol engine type performance, whereas he has just got rid of a Fiat Multipla which was a pretty sprightly car/mpv/frog, I think this lies at the heart of the issue.

Cheers

Pete
 

MartinNaylor

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May 13, 2010
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wobbly said:
I think that there being coolant in the tank when hot, but none when cold, is in fact normal operation as you say - the water getting sucked back in when the vacuum is created in the system.

I wish I'd kept my mouth shut to be honest, I cant see any signs of a head problem - we had to go out again this morning to check, stopping every couple of miles, not a bubble to be seen, no smells, nothing.

He's going to change the rad cap - will be interesting to see if going up to 1,1 gives an increase in temp on the dial - I suspect the change was made to make the engine run at a cooler temp.

His concern was poor performance ie slow, and it is slower than mine, but its done 120,000 miles whereas mines done 60,000 so its not like for like exactly.

I know this engine isnt overly powerful, but its also an old type of diesel, not the modern common rail type which gives petrol engine type performance, whereas he has just got rid of a Fiat Multipla which was a pretty sprightly car/mpv/frog, I think this lies at the heart of the issue.

Cheers

Pete
It also might be worth topping it when warm, the reservior should have water in it at all times....
Let us know how it goes...

Cheers

Martin.
 

Andy Harvey

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Mar 6, 2010
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Cheltenham, UK
Jimbo4x4 said:
Correct cap, iirc, is 1,1. I think this is pressure in bar btw. A common mod is to fit a rad cap from an MR2 which is rated to 1,3. This helps save loosing coolant on long hills etc.
Coiuld be right however on the Hilux Surf with the same engine the correct and standard cap is the 0.9 one. One of the first mods I did was to put on a 1.1 cap but it still didn't help wih stopping the cracks I had in the head.

Dump the EGR valve - it really makes a major difference to the mid range and the type of EGR fitted was a vacuum one rather than the electronic ones that now get fitted. The EGR gets blocked easily and mainly stays stuck open which kills mid range torque. That being said the 2.4 is not a power house of an engine but it does have a good torque curve and is pretty reasonable when running well. Dumping the EGR by repute helps to avoid the head cracks as unfortunately it can cause uneven head temps which is a major reason for cracking in Iron castings - one side of the combustion chamber can be considerably cooler than the other as the swirl effect in the cylinders isn't all that in the 2.4.

If the head is cracked you will know - take off the radiator cap when the engine is runing but cold and watch the geyser of water coming out.
 

wobbly

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Nov 27, 2010
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I have thought about the EGR valve before on my own truck.

I understand that if its not working it causes issues, but if its working fine then it makes no difference - so how would I know if the egr valve was knacked?

I am 100% happy he does not have a cracked head, or a head gasket issue, but things like egr could be problematic - the othe rissue of course is the turbo unit, but I'm not saying anything about it other wise I'll spend every evening staring at his turbo! But....how do you know if the turbo is working to its desired performance - is there a test that can be done?

Also....to the right of the block is a throttle control - black plastic box held on each side by a screw - does moving this affect the throttle settings?

Maybe this thread should now be called Getting the max power from the 2.4 !

Pete
 

Roger Fairclough

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Dec 14, 2010
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You need a vacuum/pressure gauge to test the functioning of a turbo. This tells you when you have turbo lag--- shows up as a neg. reading and when you have boost ie pos. pressure. To test for boost only, a pressure gauge will do. Find out the max. boost for your motor (the 3 litre is 7.4 - 9.7 psi ), fit the gauge, drive around, slot into 5th @2000 rpm, floor the throttle and boost should go immediately to max.

If there is a low reading or hesitancy in reaching max boost, first check for air leaks. If none found,next step is the waste gate. This controls the max. boost available. Once the turbo reaches it's max. pressure, the waste gate opens and dumps excess ex. gases directly into the ex. system.

As your friend is used to a sprightly petrol engined motor, he is probably unaware that the driving technique is different. Also you need to remind him that at the end of a journey, you need to let the engine idle for 30 secs. This allows the oil to the turbo to keep on circulating. This does 2 things; it cools the turbo down and maintains the oil bearing whilst the rotor is spooling down.

Roger
 

Andy Harvey

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Mar 6, 2010
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Cheltenham, UK
Pete.

To be honest if it has done an average mileage it WILL be knackered - either blocked closed (good) or blocked open (bad). They soot up something horrible over time and you either need to replace or bin it.

The black box is the electronic throttle control / Throttle Position Sensor, have never played with moving it but I guess it might affect the throttle.

Another tweak if you are confident in the engine is to space out the Turbo wastegate mounting - in effect causes the wastegate to cut in later. put say a 1mm spacer in and see how it feels - up to 3mm is probably the maximum - you don't want to overboost a 2LTE.
 
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