Going to lose my mind soon! OVERHEATING issue but bled?!

[timmyt]

Hi all,

Ok so here goes...usual story but please bear with me!
After recent overheating due to burst pipe i have replaced pipe,coolant,removed water pump,inspected and replaced with new belts and gasket (waterpump is only about year or so old and was still in good condition)removed thermostat,pan tested and found to be "lazy",replaced with new thermostat that was also pan tested and found to be working perfectly,
Successfully bled the system after flushing and replacing with new coolant and bled via correct method,all air out,heaters blowing hot,bottom hose nice and hot,took it for half hour drive up and down hills,no problems...all was fine,temp gauge at 11 o'clock,great i thought,sorted.Waited for new belts to arrive (ran with old belts in mean time) and fitted this evening.....

Replaced belts,checked coolant level,it had dropped but not by too much and not below MIN so topped up with antifreeze and started her up and left her to get up to temp.

Then i heard the Fans kick in,strange i thought,then i noticed coolant coming out of header tank overflow,not good...no hot air coming out of heater vents.
anyway thought id give her a very quick spin to top of road and see what happens,within 20meters the needle started to shoot up.stopped and let her cool a bit and came back.
After a while i removed bung on bleed hose and had nothing but steam come out.eventually it eased and i removed header tank cap and allowed coolant to flow out through bleed hose,never letting the header tank empty.
Replaced bung and started engine,expansion tank level raised until it was coming out,even with cap replaced it still came out of overflow.

So im now at my wits end with it!so am asking for advice on something i may be missing please!

Has my head cooked??!!

What is causing the back pressure into header tank?

If its an air lock why did it successfully bleed and run fine with no overheating previously??!

Thankyou in advance,
Humbly,Chris

[missfixit70]

TBH if you've had overheating issues, there's a good chance your head is cracked (mine was - similar symptoms to yours, could be bled ok, drive hundreds of miles, but airlocked again next time it started), most that just replace the gasket find it ain't long before it's all off again to do the head, even if the head pressure tests ok while off the engine. I know it's not what you want to hear

[timmyt]

Awwwwwwwwwwww.......Do you have to be so mean...chuck me a bone here! lol

I have a horrible suspicion the head is done too,just wanted to put the problem out there so someone may come back with a little hope..

Poorly poorly bongo

here is till hoping!

[missfixit70]

Rereading your post, it looks like you didn't actually bleed it properly after it airlocked? you may be lucky & it's a weep/pinhole somewhere squirting out when warm & sucking air back in as it cools. If you've had to replace one pipe (metal pipe or hose?) Chances are, you'll have to replace more. Check the two telltale holes on the waterpump during/after running too.

[timmyt]

Have replaced most of the pipes for silicone already and checked the rest for leaks,none that i can see.
didnt bleed after it overheated this evening,just removed blled pipe bung to see if there was coolant flow but got nothing but steam until i removed preeure cap on header tank.
previous to this it was bled and running fine,left it on drive awaiting new belts,replaced them this evening and noticed loss of coolant and then the overheating when taken for a spin
No sign of water loss from tell tails either.

[timmyt]

Also noticed that one side of engine (driver side) is quite wet/oily,i originally put this down to the usual oily bongo engine getting a little worse but could this be a sign of gasket failiure?

[missfixit70]

Personally I'd go for a proper bleed again, if it will, if you use the funnel method it can tell you a bit about what's going on in the system if it doesn't bleed right.
As I say, mine would bleed fine & drive for hundreds of miles (hoses would be pressurised beyong the norm though) if it wasn't allowed to cool after bleeding, but the next day, it would airlock & belch as soon as it got up to temp, head was cracked I was also getting a lot of weeps/airlocks from silicon hose connections but this tended to be in the more extreme cold weather & not sure if this was cause or effect. When I brought this up on the forum, a lot of people had similar weeping issues. may be worth pressure testing the coolant system to see if it shows up any weeps/pinholes? Got to be honest though, in your case this sounds all too familiar.

[timmyt]

Thanks for advice,think ill bring home pressure tester from work tomorrow and see what it shows.what is the normal operating pressure of a bongo do you know?
Preparing for worst though,at best its gaskets and skim,worst case new head
Can you get different sizes of head gasket to compensate for the thickness removed after skimming or is this not necessary?

[missfixit70]

Pressure cap should be 1.1bar, so don't exceed that. Around 0.6 bar is in my head for normal operating but could be wrong, Northern Bongolow is presently messing around with system pressure monitoring.

[timmyt]

thanks again.
one more thing,should there have been steam pouring out of bleed tube or is this normal?
cant recall it happening before,normally just hot coolant comes out ???

[missfixit70]

Think you've answered your own question really, shouldn't be steam pouring out of the bleed hose.
I personally wouldn't waste time skimming (worth checking the block is true though), how will you know if the head is cracked (even pressure testing isn't foolproof, needs to be up to temp really & over a period of time) or if you will end up with misallignment on the camshaft, possibly resulting in failure? (see recent examples on the forum).
May be worth trying Steel seal/ k seal or similar if you've eliminated any fixable leaks? Deends on your budget/patience/frame of mind. SS Works for some, didn't work on mine & a few others.

[mikeonb4c]

The oily stuff on the drivers side of the engine might be diesel from a leaky fuel pump seal. Mine was

Out of interest, I assume the main rad and the fron heater rad are not showing signs of blockage? But I fear Kirsty is right (I'd certainly be afeared to challenge her ) - its a head/gasket issue most likely.

[timmyt]

Hi Mike,no Radiator seems fine,well its flushing through with no sign of any C**p or blockage.
Will try some steel seal and see how it goes,if its doesnt work...time for new head!!!
Thankyou for all your help,i will post when i know more.

[missfixit70]

Oily drivers side is a common bongo feature, usually down to oily gunk seeping outa the air intake elbow/leaky rocker cover gasket, or as Mike says a bit of a diesel leak rearing its head. Worth cleaning it up to see where it's leaking from, check the rocker cover bolts are nipped up ok (not too tight).

[mister munkey]

The Voice Of Experience (I'm on my 3rd head now) agrees that the head has gone. Most likely a crack in the pre-combustion chamber in either No2 or No3 pot.

Steel Seal or something similar might give a short term reprieve but in the Real World you need to start thinking about finding around £1500 for a proper fix.

Its possible to get it done for half the money but scrimping on parts or the wisdom of an experienced spannerman tends to cost more in the long run.

Sorry to potentially bear nasty news, but life throws these curved balls at us from time to time. How you deal with it will make all the difference.