Cooling system problem...maybe head gasket

[Njkip]

My recently purchased Bis.....I've had it a few months but due to work commitments I've only been out in it twice... ( and I loved it ) It has 17000 genuine miles with lots of paperwork. I've been systematically going thro things as it wasn't running as well as it should be....so far I have found that the timing was miles out! I've set the timing with a strobe and that has improved things regarding idling and running. Despite the paperwork saying it had and engine flush and refill with antifreeze in 2017 there was very little evidence of any antifreeze in the system and the coolent level light was flickering. So my problems begin.... 😡 I've drained the coolant or should I say water! By disconnecting the lower hose on the thermostat housing, also from the three way manifold on the head and the heater matrix bleed at the front....so far so good. I've reconnected the pipes, removed the bleed from the top of rad and refilled with an aproprite concentration of antifreeze. Filled up until coolant came out of bleed on rad....I've then run the engine until up to temp ( fan kicked in) undone the expansion tank cap....at this point it it bubbled and gurgled throwing coolant out of the tank...( my thoughts were trapped air) I've bled the air from the heater bleed under the bonnet. I've repeated this process three times....taken the car for a run, temperature level fine, upon stopping can hear the coolant bubbling and gurgling, unscrewed filler cap and again coolant bubbling out of tank....oh my days! So....I can't see that there was that much air trapped in the system and felt that I'd vented it properly! I'm begging to suspect that the head gasket has blown, thus pressuring the cooling system.... is there a particular process/order to venting the cooling system? And does anyone concur with me that the head gasket might have breached.....any advice from you bis knowledgeable members out there would be much appreciated.....before I look to taking the head off.....thanks guys.....🤔

[Pete126]

Maybe a silly question but did you have the heater controls on hot and was the heater blowing hot air?

[Njkip]

Hi, yes I had the heater open and the heater was blowing hot air. I ran the bleed until the new antifreeze was coming thro, bled this a few times until I got all the air out and hot water ran. I can only think that there is air still in the system or indeed the head gasket has blown....unfortunately the symptoms do look like it...pressurising of the cooling system....thanks for your comments, much appreciated...👍

[Pete126]

Have you checked the colour of the oil if it’s milky then the head gasket has gone,
You can buy cheap head gasket testers kits on eBay which analyse if there’s any exhaust gases in the cooling system before you start a repair, I had a similar problem 140 miles from home but I always carry a bottle of K-Seal headgasket sealer which was a quick fix to get me home

[Njkip]

Hi, I've checked oil on dipstick that's fine, I've checked in filler cap that's clean. I was going to check the compression see if that's ok. It's had a new thermostat fitted recently so that's ok...could i ask if it turns out to be the head gasket then I assume as a matter of course the head would need skimming? ( I have no idea if the car was overheated in the past) looking at the paperwork it has done very little mileage between MOT's and talking to the guy I bought it from has been garaged for most of its time.

Anyway back to the head, if I need a skim where do I find an oversize gasket for it...?  I'm gonna give it another Run this afternoon and see what happens...I will say on yesterday's run it did seem to loose a bit of power on way back....I'm really disappointed now, it's a great car I've always wanted one, it's just taken the edge off for me now. thanks Pete for your help so far tho....onward and upward......maybe..😳

[Njkip]

Just an update....been out in it again this afternoon....drives ok, temp gauge between a quarter and half....stopped after about three miles....heard gurgling and bubbling from expansion tank....very disappointed 😳 Top hose very hot, don't know if this is normal for these engines?  Got back home, coolant level light on....topped it up (using hot water) I tried to bleed the heater tube and nothing came out....left the bung out for a while and coolant started to run out eventually....I've left the engine running for a good ten minutes, temp gauge just over a quarter, fan didn't KiK in at all which surprised me as it was doing before...turned engine off and this time nothing, no gurgling or throwing coolant out of filler....sooooo I'm wondering or should I say more hoping that it's been air locks in the system....I'm gonna have another run out in it tomoro and see wether it's pressurises up again....if it does it again then I'm gonna have to change the head gasket.....am I on the right track Pete....

[Njkip]

I'll check out the gas tester on eBay might be worth a go just to see first....🤔

[Gadge]

Just a quickie to put your mind at ease as I've blown a BIS once or twice over the years. It is possible to blow the gasket and not mix the coolant with the oil. This happened to me once and the oil was fine however the engine was pumping exhaust gas straight into the cooling system. Tell tale signs are the top hose expanding as you Rev the engine - even when cold - but particularly when warm as the head expands in by heat. Another sign is that after the coolant system builds up too much pressure it will beltch out coolant from the cap as the pressure relief valve gives up spewing water all down your N/S rear lamp. If you've driven about and ran it up to temprature and this hasn't happened yet then it's unlikely in my opinion that the head has blown. It's more likely that it's just trapped air OR air seapping into the system via a tiny hole or a loose jubilee clip.

They can be troublesome to bleed but this is how I do it. Undo both bleed screws (rad and heater matrix) and fill up until coolant comes out of the rad bleed squeezing all the hoses including the heater hoses coming out of the thermostat. Once a constant amount of fluid comes out the top of the rad, screw the nut in then carry on filling squeezing the hoses until the dash level light goes off. Don't worry about coolant coming out the heater bleed as it won't have got there yet. Once the light is off screw the heater matrix bleed screw in and start the engine and leave it running making sure the heater is on and set on HOT. As the waterpump pumps the coolant around periodically just undo the heater bleed screw a few turns just to let air out then screw it back in. Once it's at full temp the water will have expanded and will have reached the top of the matrix and if you undo the heater bleed you should get a full flow of coolant trying to come out (CAREFUL IT WILL BE AT NEARLY BOILING POINT). You'll have to keep an eye on the level indicator as as the air is released from the matrix the level at the expansion cap end will drop as room is made in the system by the exiting air. Eventually as air is released and the space is replaced with coolant the system will be primed of air and the fan (of which there should be two speeds) will cut in and your good to go 

[Njkip]

Hi gadge, thanks so much for your input...very helpful....👍 Some of the symptoms you relate to it being a head gasket failure have occurred. The gurgling, belching water out of filler/expansion tank...only when I removed the cap! Like I said I think or HOPE that it has been trapped air.... I will follow what you've said and check the jubilee clips seen as I've undone them to drain the system. You're right about the water bring hot at the heater matrix....😳😳😳. There is one quierie.....the engine seems to get very hot generally, not that I'm saying it's an issue, just as I'm not yet that familiar with the running of these cars.....is this how they are? I mean I drive a ford ranger wildtrak daily....so can't really make a comparison 🤔 Despite these " teething troubles" I must say it's an absolute blast to bomb about in and looking at it just puts a smile on my face...." so cute" would you be ok with me letting you know how I get on? Thanks again for all your help....👍

[Gadge]

Yes of course always happy to help.

Coolant will always belch out of a hot expansion tank on any car if you remove the cap when it's hot. This is because when water is in a pressurised environment such as a cooling system of a car the boiling point raises from 100 degrees to about 104 degrees. When you remove the cap you release the pressure and thus BOOM you get a mini volcano of boiling water gushing out of the expansion cap as the air tries to escape. This will happen on any car hence why you should never open a cap of a hot expansion cap or you could get scalded.

 In the case of the BIS once you have enough coolant in the system, all bleeding of air should be done via the matrix bleed screw as the matrix is the highest spot in the system and is where the air will collect. As the pressure builds up and the water expands its through the bleed screw it will head if you unscrew it.

Definatly check those hose clips though, any small tiny gap between the hose clips will allow air in as the cooling system cools down.

[Pete126]

Good call Gadge, squeezing the large pipes can help dislodge air locks

[Njkip]

Thanks to you both for your advice, you've been great! I'll let you know how I get on...👍

[Njkip]

Hi Pete and gadge.....just an update....after another couple of attempts I seem to have sorted the cooling system problem....been out in it today and everything seems ok, no gurgling or something resembling mount etna...😳 When I take the cap off.....I'm so pleased it isn't the head gasket....also the charging light I mentioned earlier.....made a new battery earth lead...soldered wire into connectors ....seems to have done the trick....light goes out straight away......onto next job.....need to set the tappets.....sounds like a tap dancing centipede...😳

[Njkip]

Well I think I spoke too soon.... back to square one I'm afraid....heater air locked again coolant being forced out of expansion tank ( with cap on) so I did the gas test as advised and it slowly turned green....😳😳 so I've ordered a copper gasket as opinion seems to indicate they're better! I'm just in need of advice .....HEAD SKIMMING if it turns out that the head needs skimming, can I take it that a standard gasket will be ok to refit as there will be enough tolerance.  ( I know that when a head has been skimmed oversize gaskets are sometimes used)  thanks .....😉

[Pete126]

You can skim up to 1mm off the Bis head, I had mine done by Ashby & Anderson, 191 Whitehall Road, Leeds, LS12 6EW

Refitted mine with a std head gasket.