continuos stream of small bubbles in exp. tank

[maxgreenwood]

What a day!

2 steps forward, 1 back.

After giving the TZD a service on Saturday, today I set about fixing the heater blower and after replacing the circuit board at the back from the 17TGD i got for free, it sprang to life, complete with the full-speed mod from the forum i did an age ago. I replaced the wiper motor while i was in there with a spare i'd got ages ago, mine was flappy and now its nice and fast and tight. So 2 good results! ....but...

I have also noticed in the last couple of months frothy bubbles in the coolant doesn't smell fumey and the cooling system retains pressure overnight, doesn't pressurise too quickly after starting so i was hoping it wasn't the head gasket or the head. And it wasn't like this after i'd had it in the garage for a difficult hose change, the only thing i've done since is replace the small thick thermo housing hose and refilled and bled. I thought maybe i hadn't bled properly this last time... So went about bleeding with a head of water in a bottle on the exp tank..., took 'bleeding' ages to get engine up to temperature, I had it idling for about 2 hours then with the fans cutting in and out. The rad didn't heat up uniformly - about a sixth of the rad - the middle lower half was behind the rest in warming up so i think there may be crud in there - i'll have to flush it at somepoint.

No matter what i did i couldn't get these bubbles to stop. At one point i had a disaster and sheared the head of the hex bleed screw off on the thermostat housing! - it pissed it out over the front of the car. Luckily the 17TGD had a spare!

My heater matrix has been weeping coolant through the bottom ducts near the footwells in the front - and i have a new matrix to fit when i can (aided by the invaluable advice given here on the forum), could this leak be the cause of the air? , that is if its not combustion gases.

I have searched the forum for wisdom on these symptoms and it looks like i'd have to get the exp tank 'sniffed' at a garage for gases to be sure.

Where else could air be getting in? The water pump?

if a hose is not dead tight on the jubilee clip somewhere, would that cause air and bubbles?

Any advice would be much appreciated.

I'm looking for an answer that doesn't include the words head or gasket or block or fubared

The car runs great, a bit lumpy and lots of white smoke on startup for a minute - i read that can be caused by cracks in the head...but loads of power. Bit smelly from the exhaust.

[DavidRutherford]

Usually a continuous stream of bubbles in the coolant does indeed spell head gasket death.

However, the fact that the system holds pressure overnight and doesn't pressurise straight after startup would suggest quite the opposite.

If the engine has just been running, and you release the coolant pressure, is it the normal small "phut" of pressure release, or does it explode?

[maxgreenwood]

well it doesn't explode exactly, but its pretty lively if you take the cap off quite quickly.
The coolant does belch air bubbles out whenever i take the cap off - it shouldn't do this? Maybe i'm taking if off too quickly.

Should there be no pressure in the system after about 1 or 2 minutes running from depressurized?

[maxgreenwood]

i just took the cap off after the cars been standing for a couple of hours after a good run. Small 'phut' of pressure release followed by a few bubbles rising from the depths.

[Geoffrey Gould]

Hello Maxgreenwood it could be a +++++++++ well you said not to mention it but before anything else I would seriously get the radiator sorted because it sounds semi-blocked and that will with out doubt will kill the engine for sure.Known it happen too many times.
Best of luck.
Geoff.

[BX Bandit]

/\ definitely what Geoff said (although make sure it's not an airlock albeit unlikely in the area of the rad you mention)

The lumpy idle & start could of course be glow plugs & associated relay/control box (it the blue box on the passenger side wing inside the bay - do you know they are all ok?). It depends how lumpy it is. With cold starting/glow plug issues the starting idle is rough but sort of coughy. If water is getting into the combustion chamber somewhere, then the start idle is somewhat harsher but it's not very obvious a difference unless you've heard both.

Something to try max....
1) with the expansion tank cap off, rev it gently whilst watching the expansion bottle BUT at a distance first as the escaping gasses can be enough to surge the coolant at you. Once you are happy you're not going to get coolant in your eyes, rev it gently whilst watching the bubbles. Do they increase or change size when you rev it? If so then the prognosis is not good!

-What you really need to do is consider the worst case scenario and decide if you can afford to fix or whether you still want to keep the car.
If you can/do, then drain the coolant system and do the heater matrix. Fill it up back up again and satisfy yourself you've bled the system.

-If the rad still has a cold spot then you need a new rad if the longevity of the car is to be secured.

-fit new rad and any hoses that may be suspect, bleed system. Make sure all hose clips are tight - get new jubilee clips and don't use cable ties!

If your bubbles persist then tis almost certain to be gasket or head. After that then you have the issues of was it gasket or head? Shall I get the head tested and skimmed? or shall I scource a good 2nd hand unit?

Now find a nice point of Guinness and soothe you're furrowed brow

It's a shame you're in fuppin Ireland Maxxy Priest!




N.B. Edited part in italics

[Geoffrey Gould]

Wise words Mr Bandit in these days when every penny counts, it all mounts up.
Cheers.
Geoff.

[BX Bandit]

Max Max where are you Max?
Are you sending a Fax?
Or writing a song
for us to sing along...............to
der da der dum dum der da der

[maxgreenwood]

Hi Guys,

was away from internet Fri Sat Sun, down in Wexford on a job recording.

Thankyou for all your doctorly concern, hopefully we can get a good diagnosis before considering my next step...

Ok done a few symptom checks:

losing no coolant
not much pressure build up in coolant after starting engine after 1 or 2 mins, some after 3 minutes and some more after 5 mins, but just slightly and progressively.

at idle there are waves of tiny bubbles coming to the surface every 2 secs or so. When revved slightly some bigger bubbles appear, then no bubbles for a while when throttle released to idle, then resuming after a few seconds. The volume of air or gas doesn't seem to be changing as i rev the engine, it might be slightly, i could be wrong about this, difficult to tell.

After engine fully warmed up, the bubbles actually stop when engine is revved and resume a continuous stream when idling.

The expansion tank does explode and froth coolant when taking cap off quickly after a run the other day, but if you do it slowly it doesn't spew out.

a question - should the radiator warm up steadily from a cold engine, or does it only get filled with hot coolant when the thermostat opens for necessary engine cooling as its needed?

mine stays cold for about 35-40 mins after startup and idling in the drive and then starts to warm up after 40 mins. It then warms up from the top down.

The top of the black plastic tanks on either side warmed up though before this after 20-30 mins.

Does any of this tell me more?

Tell me more!

[maxgreenwood]

i'm considering something like k-seal maybe after a system flush and rad backflush.

[BX Bandit]

Sounds like porous head mate I would say. Maybe gasket but I'd expect not tiny bubbles and more of a difference between idle and revving. The only explanation that....er......explains no bubbles in the header tank during revving when hot is the increase in pressure due to both warming and revving within the cooling system is enough to prevent the gasses passing through the small area or porosity in the head!

There's always a flow through the rad, but it's kept small until the thermostat opens. On idle then 30 - 40 mins is too long for the thermostat to open, but about right before you begin to feel the hotness in the rad. (If you feel the large hose coming from the thermostat housing that should begin to feel warm after 10mins or so at idle.

To really check the rad, you need to leave it idling until the fans kick in - about 60 minutes - there should be NO cold spots!

[maxgreenwood]

Hey Bandito, thanks for getting back so quick.

the top hose does begin to feel warm after about 10 mins. The rad definately gets hot all over after 60 mins, just from the top down, the bottom is slower to heat up - could have some silt in there.

what about K-seal - good for a porous block?

and would you recommend a coolant flush agent before this?

I have a new thermostat here i could fit and a couple of new hoses, including big bottom one. then i could check the rad with boiling water, fit back together before K-seal.

[BX Bandit]

K seal will do your heater matrix and it's 'supposed' to do your head BUT, AFAIK it works by the pressure within the cooling system forcing coolant out of the leak. In K-seal there are sealant 'bits' which are forced out through the leak and eventually block it. So logically, the only way it can work is for the engine to be turned off when hot. These stop leak things have rumoured to add to blocking of small/already restricted pathways within the cooling system and may provide several 1000s of miles of trouble free motoring......and it may not!

Worst case is that your system is already partially blocked, which means the system hasn't been maintained properly so the build up and partial restriction of waterways has already taken place. So, if the rumours are true (about stopleak stuff) , then you are putting off the inevitable which is reduced cooling efficiency and so higher risk of future head trouble.

Having said all that, K seal is supposed to be the dogs danglies in the world of stop leak stuff and you may get a good few years out of the car yet. It could also be the head gasket rather than the head in which case the proper fix is cheap (for parts) but still rather involved. In this case it boils down to £££££ vs longevity

With the rad, you have to satisfy yourself that you got the engine hot, the cooling fans came in and that the whole rad was hot. If it was, then a quick flush with the hosepipe should suffice. I've never used a flush before BUT I assume it's meant to help dissolve calcium carbonate (like in your kettle) build up and other gunk which on a gasket which has seen dubious coolant maintenance I would advise against it.

Others may have used it good effect mind so don't take my word for it. In fact, anyone please correct anything I've got wrong for the sake of Max!

BTW, highly unlikely you have porous block but porous head.

[maxgreenwood]

i've already spent a fair bit of time and money on this car so i'm reluctant to spend loads more if i can help it. Its in pretty good nick but has early rust starting in the usual areas, all minor and fixable i think. But all in all, i think i'll use it as long as i can and look out for another good one and grab it if one comes along - estate owners bear me in mind!

the rad is hot all over when engine is up to temp and the fans kick in. flushed the rad in-situ last year, but i'll take out and backflush, replace thermo and other bits then try k-seal. need to get the other lower temp fan switch also.

One of the niggles with the car is the ride, although its got loads better since flush and LHM and lubing struts its still a little bumpy on small undulations. I know the struts are sometime sticking/binding - i sometimes get the drivers side one sticking lower than the passanger's side leading to uneven looking heights on the front roadwheels. And I suspect the height correctors being gunged and sticky in their linkages are also a problem - Myself and Robin (citroen7) from NI have a plan to get together and put on refurbed struts, reconn the height correctors and replace the brass bushes etc, so i think this should sort the ride hopefully. Tick time has been creeping faster to about 4 - 11 secs now, so a few things to look at there - high return to LHM tank on brake lines. other things, octopus at some stage, front to rear HP pipes a bit rusty. All in all not too much. If i have success with the cooling system stuff i'll move onto the other stuff and look at the rust and should go for a good few years more. if not i'll have to weigh up whether to change the head/gasket.

[DavidRutherford]

Just occured to me... is the car actually using coolant at all? If not, then there may be hope that it's not the head.