Weird Engine Issue

[Ashy]

Following on from this thread (http://www.rtoc.org/boards/showthread.php?t=14610), Brigsy kindly sent me a blue expansion cap up to try on my car... For some reason on a full throttle run the brown cap I was using released and sprayed coolant onto my engine. Anyway so I fitted the blue cap and went for a long run tonight, and again the same thing happened!

Anyway so I assumed the worst that somehow I had a head gasket issue. Thing is the cars not smoking, theres no mayo under the cap. So I whipped the plenum off and did a compression test. Results were 160 - 168 - 166 - 168 psi on each cylinder... So now i'm stumpped... Anyone got any ideas?

[Tony Walker]

Is the coolant circulating properly(thermostat opening and flowing through the rad)
Not overheating at all?rad fan cutting in at correct temp? are you overfilling the header tank, it needs room to expand?

[dave j gtt]

bad water pump maybe. or bad thermostat ? try running no thermostat see it pressure eases. :scratch: ermm bit of a tricky one, hope you get good news and easy fix ashy.

[J$£5GTT]

maybe a blockage in the system s'where?

:)

[JRP]

Possible blockage, i know you know your stuff, but has somthing been overlooked? on incorrectly? heater matrix condition? rad condition...

could flush it all out remove all pipes rad etc and give it a good going over...

:confused:

[dave j gtt]

Am geussing this is the 2.0 16v, Any one else with this conversion have these probs in past or any one with normal aspirated car ?

[Ashy]

Some good points there thanks. I have run this engine before and not suffered this problem, however I've made some changes since fitting the new turbo... Like you say maybe somethings been overlooked. Will check the the coolant pipe run aswell see if I've connected something up wrong...

Cheers.

[TNT Tricky Nicky]

I was thinking heater matrix, same as jrp but before I read it, maybe it's causing a restriction leading to excessive pressure. Not sure if the clios are bigger than the 5s?

Edit: as in blockage, a blockage in a Clio matrix may not Be as bad as in a 5s due to flow rate if it's bigger?

[Shane P]

I was thinking heater matrix, same as jrp but before I read it, maybe it's causing a restriction leading to excessive pressure. Not sure if the clios are bigger than the 5s?

Can it be bypassed to rule it out? Out of curiosity :)

[TNT Tricky Nicky]

Yes, take both pipes off and put a joiner in.

You may notice the engine running warmer as the matrix
aids cooling

[michael tierney]

sounds like ur rad is blocked,check for cold spots on it with your hand..especially at the bottom.Comp.pressures may not be effected by a blown gasket,if the car misses a cylinder on startup its usually a good sign there's water in there!

[Rob@Backyardracing]

Id say head gasket issue. If you had a blockage etc you would expect to have hot and cold pipes here and there, and if peeps are thinking a flow issue to pop the cap it would re act that by just reving car on the spot once hot...

Id be looking at head gasket simply due to your only having the issue when your cylinder pressures are at there greatest and not at any other time.. One thing you could try is get the car stinking hot (be carful with this) but rig up a pump the cap and add even more pressure to the coolant, and get a camera down the bores and have a look.. its a tricky one to do and might show nothing as your never going to be able to match a cyl pressure to get the coolant to leak in to the bore, Hence why you probly never have starting issues etc..

Or another check, messure the amount of coolant being lost in a bottle, re torq the head and increase the torq, go out and re messure the lost amount..

[Nick k]

I would say there's two causes to this, Either

1. Compression is getting into water jacket/system and pressurising the whole water system which points to head gasket or a hair line crack in the head itself. You wont always get mayo if its only gone between cylinder and water jacket!!

2. Its getting too hot in the block/head when on full load and boiling the water causing it to blow it out the bottle.

Have to done a pressure check on the water system when cold, when you pressurise the water bottle with a pump and monitor a gauge to see if its losing pressure anywhere in the system? as suggested above

[Ashy]

Looks like its sorted, I'd run a new pipe from the back of the thermostat housing which had a big kink in it. Found a few nice silicon bends and made the necessary changes... Been out for a few full throttle runs (although struggled with grip on the damp roads) and all seems to be in order :)

I have pressure tested it when red hot and theres no problems with coolant getting into the bores, I took it upto 40psi!

Im hoping it will be dry this week so I can get out and really load it up :agree:

Thanks for the help.

[SP33DY]

Glad it's all sorted mate, looking forward to getting a run out in it once it's fully mapped.

Might spur me on to sort mine out a bit quicker :scared:

[Ashy]

yours still in bits like Steeve?

[SP33DY]

Yes mate, I really need to remove those studs and pop them through to my ever so friendly machinist to have them turned down to M8 threads :laugh:

I've just ordered the rest of my silicone hoses, in addition I need to speak to Scoff and get a

Hall effect speed sensor (for my rear ABS ring to run speed sensitive boost settings)
Air temp sensor
Coolant sensor
Suitable plugs for them
A TPS sensor for a Jenvey throttle body

And a few other bits and pieces but I'm going to double check everything tomorrow before I place my order as I always seem to forget something LOL

Then I simply need to wire in my ECU and fit the turbo and exhaust, oh yeah and my zeitronix wideband display. Probably an hour or 2's works there :sad:

[Matt Cole]

I would say there's two causes to this, Either

1. Compression is getting into water jacket/system and pressurising the whole water system which points to head gasket or a hair line crack in the head itself. You wont always get mayo if its only gone between cylinder and water jacket!!

2. Its getting too hot in the block/head when on full load and boiling the water causing it to blow it out the bottle.

Have to done a pressure check on the water system when cold, when you pressurise the water bottle with a pump and monitor a gauge to see if its losing pressure anywhere in the system? as suggested above

Point 2 would be worrying in that as water boils at 1 bar atmospheric. The system is pressurised (max pressure relief 1.1bar? (gauge pressure) so the water would have to be above 100deg c to boil. Albeit its not unheard of if there is a blockage and system pressure cant be maintained.:eek: