11 replies to this topic

[zero_wlv]

I have a rebuilt engine which has currently covered 180 miles.

There are a few tuning-related teething problems which I'm hoping will get sorted out at the rolling road at 500 miles,  but other than that everything seems to be going ok.

 

However one quite worrying thing happened today - I was trying to restart the engine (which was already up to normal running temperature).   It usually takes about 10 seconds of cranking to start.    This time,  after a few seconds,   steam started to appear in the cabin from the bulkhead area!   Next thing I saw was some steam escape from the right hand side of the bonnet so I swiftly opened the bonnet to see fairly large amounts of steam escaping from the air filter!   (A Ram-Air foam filter).   

 

Obviously this was quite worrying so I spent 10 minutes doing various checks and deciding whether or not it'd be safer to get the car trailered home.    The one thing I did notice is that the fuel filter was completely empty so this was presumably the reason for the failure to start.  After a while I decided to have another go at starting,  and it started perfectly without any problems and ran the rest of the afternoon as though nothing had happened.

 

I can reasonably assume that the cause of failure to start was fuel starvation,   but how the hell can this lead to steam pouring out of the air filter?   

 

Is the only possibility a head gasket problem,  and if so,   why did it only happen when I tried to start?

Coolant in the radiator is at normal level,  so I haven't lost coolant  (it is,  however,  alarmingly dirty considering it's only covered 180 miles - see pic below  -  and bear in mind the radiator's brand new).

Also,   it consumed about 0.25 litres of oil during the last 90 or so miles.

 

This problem only happened once (this morning) and nothing similar has happened since.

Is it ok to drive without further investigation or should I be taking the head off?

 

Thanks in advance for your advice.

Attached Files

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Edited by zero_wlv, 23 December 2017 - 11:39 PM.

[nicklouse]

Who rebuilt the engine?

[zero_wlv]

Who rebuilt the engine?

 

A-SD in Derbyshire.

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[sledgehammer]

what could have happened is the engine kicked back ,

 

the compressed air / fuel was pushed back into the inlet manifold , thru carb & out air filter - it can look like steam

 

that is the only thing I can think of if you havn't lost water & engine runs smooth

 

however that coolant is bad for a newly built engine with new rad etc - I guess the crud/rust is flaking up from the bottom of the water jacket as it dried out

 

I assume they havn't washed the water jacket , or the rusty colour is from the heater matrix

 

I personally would ( if the engine is running ok) do a compression check - easy to do

 

get engine hot , flush all the coolant out , connect a hose to a heater pipe & slowly force the crud out of the system

 

then connect the hose the opposite way & flush again (you may have to remove thermostat for it to work better}

 

refill with water , go for a run - see what colour the water is drain if necessary until better

 

use good antifreeze / corrosion inhibitor when it is clean enough

 

best of luck 

 

edit - some say use distilled water in the rad - but I think it was tap water from the factory - up to you

 

also did they re torque the head - reset the valve clearances ?

Edited by sledgehammer, 24 December 2017 - 12:04 PM.

[zero_wlv]

what could have happened is the engine kicked back ,

 

the compressed air / fuel was pushed back into the inlet manifold , thru carb & out air filter - it can look like steam

 

that is the only thing I can think of if you havn't lost water & engine runs smooth

 

however that coolant is bad for a newly built engine with new rad etc - I guess the crud/rust is flaking up from the bottom of the water jacket as it dried out

 

I assume they havn't washed the water jacket , or the rusty colour is from the heater matrix

 

I personally would ( if the engine is running ok) do a compression check - easy to do

 

get engine hot , flush all the coolant out , connect a hose to a heater pipe & slowly force the crud out of the system

 

then connect the hose the opposite way & flush again

 

refill with water , go for a run - see what colour the water is drain if necessary until better

 

use good antifreeze / corrosion inhibitor when it is clean enough

 

best of luck 

 

Hi Sledgehammer,

 

thanks for that,  that's (potentially) re-assuring,  if that's what happened.     Immediately after it happened the fuel filter was completely empty though so I don't think there was even any fuel getting through,  unless there was still some left in the float chamber but not enough to start successfully.    It does seem to be a complete one-off as it hasn't happened before or since.

 

As for the coolant,  I did realise overnight that although the block and radiator are both brand new,  it's been flowing through my 30 year old heater matrix which I would imagine won't be in the cleanest condition,  as you say.    Even so,  the state of it is still a bit concerning.

 

This afternoon I'm busy dealing with my other problem (the mysteriously damaged dipstick) but hopefully I'll find time soon to fill with fresh coolant and see how I get on with it.    If that ends up the same way,  I'll try flushing the heater matrix as you suggest.

[CityEPete]

I'd be tempted to pop a new matrix in, I swapped mine and the lack of damp dog smell and improved interior heat was well worth it. No matter how much flushing back and forth I did the rad water turned brown, it's nice and blue these days.

[Kt1966]

You can pick up a matrix for a Metro which in my experience is a lot cheaper than buying one from the mini specialists

[cal844]

You can pick up a matrix for a Metro which in my experience is a lot cheaper than buying one from the mini specialists

I bought an all metal one for a 1993 mini for well under £50 delivered, from eBay

Edited by cal844, 25 December 2017 - 11:11 PM.

[zero_wlv]

Thanks everyone. I'll have a look for a new matrix at a reasonable price. At £50 or under it makes sense to just replace it, I'm not sure it's worth trying to flush the old one when I know it's 30 years old and seems to be producing that much brown gunk.

As for the steam incident, I've driven another 110 miles since then without incident so I've relaxed about that now, although I have remembered to put the fire extinguisher back in the car, especially as Sledgehammer suggested it could have been starter kickback i.e. fuel vapour! (thank God I'm not a smoker!)

Edited by zero_wlv, 26 December 2017 - 11:46 AM.

[zero_wlv]

One more question regarding the difficult starting that lead to the steam incident:

 

I'm pretty sure that this is due to fuel starvation.    I have a fuel filter that's fitted on the bulkhead about 1 inch higher than the fuel inlet to the carb.   I fitted it here because it seemed like the most convenient place on the bulkhead and I didn't think it being slightly higher than the carb would cause a problem.    It would seem that when the engine's off all the fuel drains out of the filter and when I need to restart it takes about 10 seconds of cranking to fill the fuel line again.

 

I've probably answered my own question and shouldn't really be asking,   but will the problem be solved by relocating the filter to somewhere lower down?    Or could it actually be caused by the length of the fuel line between pump and carb now being much longer than before I fitted the filter?   (It's at least twice the length in total and quite a bit of it is hose rather than copper tube,   the hose having a substantially larger I.D.).

[sledgehammer]

sounds like the fuel filter is letting fuel run back to the tank (lowest level)

 

then cranking pulls the fuel back up - the filter can make this look worse , as usually you see the top of the filter where the air is

 

it could be the fuel pump valves getting weak / rough (ethanol seems to kill em)

 

another simple thing to check is take filler cap off - does it change anything

 

you can get a one way valve to stop the fuel running back to tank - may help things , 

[nicklouse]

Steam out of the carb is a head/head gasket issue.

Vapourised fuel being kicked back out if the carb can look like steam.