mje_wrx

iTrader: (6)

driving steady today, cud smell burning oil, then came to junction, car cut out n steam came from under bonnet everywhere. had to get towed home, done a compression test and all 4 cylinders are 50 - 60 psi which is very odd. but when driving it was fine, temp stayed half untill it cut out n then decided to jump to H. no smoke out of exhaust, was driving perfect.

its odd all 4 are low. was built 4k ago, wiseco pistons, new rings, rods n bearings. never had a issue untill today and no warning. just cooked.

i removed all spark plugs, intercooler pipe as its fmic and was in way. tester in, foot on throttle and cranked engine.

any ideas any1

my worry is why it cooked in 1st place.

also has cometic 1.6mm head gaskets - which being metal and multilayer i cant see them blowing

thanks matt

TonyBurns

iTrader: (3)

How much oil is in there? are all the levels good? any undue knocking noises?
Any warning lights come up on the dash? do the gauges show any abnormalities???

Otherwise its probably strip the engine to see if something has gone....

mje_wrx

iTrader: (6)

oil is good, water not alot left, gauges all showed good untill it cut out, then when went to to hot. no warning lights.

Splitpin

Have you checked the cooling system for pressure integrity/leaks? It isn't something like a cracked rad/holed softpipe/loose clip?

Also re. your comment in post 1 about the head gaskets, any gasket can fail. Very rarely you can just get a bad one, and there's also the obvious question as to whether the engine assembly procedure was correct in the first place.

Is this the first compression test you've run on this engine since the rebuild, by the way?

prodriverules

iTrader: (52)

what was done to the block before the forge pistons were added mate?
And who done the build,you or some 1 else?
sorry to hear this as well mate

mje_wrx

iTrader: (6)

well i built it, following scooby manual word for word. no leaks etc. im thinking water pump failure. soon find out tomorrow. gonna take it apart. sh*t happens i suppose.

markjmd

iTrader: (11)

General question on compression-testing - how tight does the adapter have to be screwed in to the plug-port to give a reliable reading?

mje_wrx

iTrader: (6)

yeah first test. engine was cold tho and forged pistons. so not the best, but car wont start. never mind. joys of scooby ownwership.

tjmatt

iTrader: (1)

Water pump seized and made the cambelt slip a few teeth? Incorrect cam timing or the resultant bent valves will cause low compression readings.

tjmatt

iTrader: (1)

Hmm thinking about it I don't think the water pump uses the toothed side of the belt so probably not that...

mje_wrx

iTrader: (6)

at 80mph it cud be possible tj. not check it yet, misses ill, so looking after the baby. soon as i do il post up

mje_wrx

iTrader: (6)

quick hour stripping it down, timing was spot on, water pump feels good, oil is ok, wasnt much water left in it tho. rad looks ok. so tomorro engine out and start again.

very weird this. cant find any failures yet.

ALi-B

iTrader: (1)

Does sound like your head gaskets are cooked, but for that to happen there usually is another fault that causes the gasket to blow. Otherwise it could be a cylinder liner issue, but I seriously doubt it.

Blown/leaky hose, or maybe the water pump impellar has come off the spindle (or is spinning independantly of it). Its either something that has caused an air lock to build or the pump to stop working.

The problem with the temp guage is they aren't accurate; for two reasons. The way it works is it will only jump up to H when its is actually well beyond overheating, it doesn't gradually climb to H. It'll stay at the normal postion then suddenly shoot up to H. The Second issue is the sender relies on teh presnece of coolant to give an acurate reading; if their is no coolant (i.e air lock etc). It'll read normal even when the engine is overheating.

The above is not really of much help now, but its something to keep in mind when messing with the cooling system.

As for the compression tester; just need to be finger tight, and make sure the O-ring is in good condition (if its perished it'll leak, if its over tightened, it'll pinch the o-ring and leak, but that will show up more on a leak down test).

mje_wrx

iTrader: (6)

thanks ali-b, thats my thinking also. so far all iv checked is ok. but i really need 2 find the fault. or it will worry me when re assembled. didnt realise the gauge wasn't very accurate. do u have any recommendations of a more accurate system. doubt a prosport gauge for instance would make a difference if it runs of standard sensor.

as i find more out il post up. see if i can puzzle it together.

mje_wrx

iTrader: (6)

after strip down found nothing wrong engine wise, but split on rad top hose a split has caused all this, depressing. lol

LegacySTi

iTrader: (13)

that wouldn't explain 50-60psi on compression test..

mje_wrx

iTrader: (6)

no, but forged pistons should be warm to do test, iv no doubt block is solid, heads are going off for sorting tomorrow, valves checked etc. gaskets were in a state. the compression issue doesn't worry me to be honest. all pistons and bores intact, no marks or scores. and blown head gaskets will cause low compression, and these gaskets are blown bad

ALi-B

iTrader: (1)

Not really. Most need the presence of coolant to give an accurate reading, if the engine loses its coolant, the sensor just isn't accurate. A level sensor in the header tank would be more helpful.

What I do have is a hand held laser temp sensor and point it various parts of the engine. Areas that I know contain coolant should be at or below 100C degrees (thermostat housing, top rad hose, heater hose etc), anything above 110C degrees and its time to turn the heater on full or turn off the engine.

I tend to use the above when dealing with Rover K-series which are prone to air locks after the cooling system has been refilled (especially MG-Fs).

Obviously thats no good if you are driving the car though.

mje_wrx

iTrader: (6)

makes sense. i did find a sensor adaptor for the top hose. but as u say, no coolant, no reading. wonder if any1 has fitted a level indicator in tank. cant see it being very difficult.