Had a bit of an issue on sunday. Heard a popping sound followed by a 'hisss' when i was overtaking and on boost. Pulled over - shut the engine off and for a good minute or so, it was 'hissing' from the rear of the engine somwhere. I couldn't see any coolant anywhere but I could smell glycol. As I was driving it home on the highway. Within 30 seconds or so, temp jumped up to max, missfiring, backfiring and I could hear a rather unplesent rattle at low rpm and under slight load. So I shut it off, rolled to a stop. Opened the hood - the entire engine bay was smoking. Got a tow the rest of the way home $$. Over the last few years, I've noticed its been drinking water - but I've never known were it was going. Radiator was always holding pressure fine. Just a few weeks ago, I topped up the rad and filled the overflow. When I got home I can see the rad is now only 2/3rd full and overflow bottle is empty. Did a pressure test and it can't hold pressure at all. All I can hear now is air flowing out at the back of the engine or LHS turbo area. I will be doing a compression test tonight, but I couldn't hear or see any water coming out of the spark plug holes. I have brand new heater hoses and turbo coolant hoses when I deleted all the crap on the plenum. Pending the compression test, what do you guys think the problem might be? I haven't been able to find where the leak is, so I'm thinking I might refill the rad and pump it up again and hopefully I can spot where the leak is... Though I'm a little hesitant because if it is the HG, I don't want to be pumping water into the cylinders. Lastly, if it is either HG or turbos, would it be easier to yank the engine out or work on it in place? I've heard that getting the heads off is a PITA... and turbos are almost impossible to get off? Will post an compression update later tonight. Cheers.
Could be head gasket. How's your oil look? What about your plugs? Any smoke when running out of the exhaust? But with an audible leak at the back it seems more likely to just be a coolant leak. Hoses, hardpipes, even turbo body. Heads and turbo can be removed as one piece while the engine is installed depending on the size of your turbos. 2560R's will just fit out. RS's I don't think would. Remember to remove those stupid little 10mm bolts along with the headbolts. I would pull the engine though.
Haven't checked oil yet. plugs look fine. not wet. I didn't notice any smoke out the exhaust. I also couldn't hear any air from the tail pipes when I was running compressed air through the rad. It does sound like a coolant leak somewhere at the back, but as you know, its quite tight back there. I'm not sure about where the coolant passages are under the plenum either. Fortunately/Unfortunately, they are stock auto turbos. They've been tuned to 15psi as well. So I guess that means they'd be easier to remove? Though if I replace them with something bigger, getting them back in will be a challenge. Having said that, depending on what the cause is, just not sure if it's better to remove the engine or not. Knowing me, I would waste 100x more time trying to turn a hard to reach bolt.
Start by pulling all the spark plugs and seeing if any are covered in oil or have been washed clean by coolant flowing into the cylinder. If possible do a compression test or leakdown test while you're at it. If you're willing to invest the time in the car then pulling the engine isn't a bad move for most of the possible causes, get all the tricky coolant and fuel lines replaced plus finish off any deletes etc. and do upgrades if you want. Also have a look under the carpet in the cabin and see if the heater core has been leaking
Sounds like you have the tools to pressure test the radiator. Fill it up and apply pressure, if you can't see any water leaking on the ground but you can hear it then the leak is internal. Disconnect the exhaust from the turbo's or dump pipes and see if it leaking out there. Drain the oil from the sump see if it's leaking out there. Has to be leaking out somewhere Does the oil look milky? Does the water look dirty/oily? Remove the spark plugs, pressurise the rad and turn the engine over by hand see if any of the plug holes fill up with water. Oh and as has already been suggested, check if the carpet up behind the dash is wet, or any of the heater box ducting.
Well... I've royally effed up... Such a stupidly small mistake has cost me big time. If I was employed in a workshop, and did this to a customers car... I'd assume I'd get sacked for this armature fluff up... Good news though: At least it isn't the head gaskets... But I'm not sure if this is worse or not... Turns out when I was in a bit of a rush slapping the gearbox back in, I didn't notice a pesky grounding eyelet managed to only just sneak its way between the top of the block and bellhousing when I wasn't looking (not that one can see anyway). When I did up the bolts, the crimped cable end has kinked/crushed the rubber LHS turbo coolant return hose. I've probably only gone through less than about 5 tanks of fuel since then... but its maiden run was sydney motorsport park... and its last trip was to Canberra and back. In its last moments, the entire coolant hose has split all the way through and its dumped 1/2 or so of the coolant over the top of the gearbox over about 20kms or so. So I guess what I thought was smoke was luckily just steam. Considering that it would have been starved of coolant since december last year, I'm worried that I've damaged the turbo from over heating. Perhaps the low rpm rattle I could hear was from the turbo? or maybe thats what the engine sounds like with an empty water jacket? I'm hoping that since the leak is on the water pump inlet side that the water jackets were still full of water and that the sudden rise in temp was just from the sudden decrease in pressure when the hose blew? So I think that the very brief over heating hasn't damaged pistons/rings/bores or I that I didn't have hot spots on cylinder walls caused by bone dry water jackets...? Would this have caused the bad missfiring and backfiring it had in the last few seconds? If permanent damage to the turbo is most certain, then maybe its a good opportunity to upgrade? Well I guess this also explains the mild clutch shudder I was getting recently, though I'm still not sure why this engine has always liked to drink water ever since I've first owned it. Maybe there is more to it? The next challenge will be to reach the bugger. It's probably in the worst possible spot. Well, at least its not under the plenum.
Oh I forgot to mention the compression numbers. Not perfect... #1: 145 #2: 145 #3: 125 #4: 140 #5: 135 #6: 150 Manual says TT should be at 170psi nominal and no more than 15psi maximum difference. And minimum of 130psi. It looks like #3 could be a potential problem? If left like this long term, could this cause uneven loading/vibrations on the crank? I assume that wouldn't be good. Maybe it's due for a rebuild? maybe I'm just looking for an excuse to pull it apart? maybe I should exercise self control considering my history of quality workmanship...
Don't try to change hoses like that with the engine in, you'll end up with even more problems. Pull the engine out and do it properly.
15 psi difference usually means rebuild but 25 psi difference .........engine out and do the whole lot at the same time, As you want upgrade anyway do a freshen up of the motor and you'll smiling for years to come
Have you got any compression figures taken prior to your loss of coolant episode? If you have you should compare them against your latest test. The misfiring etc would've been related to the engine overheating. The engine oil would be stuffed too. The engine needs a rebuild based on your latest figures. Change the oil, fix the leak & drive it around normally while you save up for a rebuild. You may get another couple of years out of it. Don't worry about the compression damaging the crank.
Previous compression were mainly around the 140~150psi range. I don't remember seeing one as low as 125. 135 maybe at the lowest, but this is from memory - 2 or so years ago. I've got rego next month, so I'll just patch it up until I get the pink slip. I wont really drive it in the mean time. Seems I'll have to get used to the idea of spending some money and time on the neglected engine. Pretty much everything else has been worked on as I've put handling/control > raw power. I'm sure even just refreshed compression on stock turbos would make a huge difference. Is/was only 244rwkw a few years ago. Probably less now.
Yours wouldn’t be the only Z with low compression. If you have the $$ and the resources it’s a good excuse for rebuild. Otherwise fix the hose refill the coolant change the oil and off you go. No need to pull the motor to replace the hose.
The engine rattle you heard at low RMP is called 'the death rattle'. I guess in the meantime, you could do an oil change and see if the oil is milky. If yes, don't bother with anything else. If not, replace the hose that's damaged, top-up with fluid and see what happens. If you can still get away with driving it, perhaps start to look at rebuilding another engine. Peter
'The Death Rattle' ... Is that the good kind or the bad kind? Jokes aside... I assume you mean it was pinging that I could hear?
When the motor severely overheats, i.e. 'cooks', it starts to seize. The noise that it makes is similar to pinging/rattling and gets louder and louder if still being driven while overheating. If you had persisted driving it, it would eventually just seize as soon as you stop, say at a set of traffic lights. You won't be able to crank the engine after that. Been there done that thinking it was the g/box making noises. In my case, it was not a Z 32 design issue as such but an owner issue where the previous owner used plain water as coolant and rust formed inside the motor causing a hose blockage. Once the motor cools down, the noise should go away (it did in mine) but normally, there will be a head gasket issue after that. Peter
So I assume the sound was coming from pistons/rings jamming up on the bores? Oil pressure never dropped, so it's safe to assume bearings would be fine? The rattle was only very slight and fairly quite and only for a few seconds. 10s tops. The wife couldn't hear it but I guess my ears are tuned to it. I've noticed though that there's been some rust build up too. My brand new silver gearbox is now orange, and my new alloy radiator is dark brown inside. I've never filled with tap water. Rinsed, yes, but I've always filled with distilled water or premix. So what's the best way to flush this crap out? I've done the vinegar flush on motorbikes but with mixed results. (barely does anything) I know old boiler tubes are washed out with hot citrus acid. Though I don't exactly want to make holes in my heater box etc. I assume there would be an old school method that I'm not aware of. I wonder if phosphoric acid would be any good? Great for rust and alloy oxides when used briefly and is safe on copper...? Though I doubt it'd break down calcium phosphates from hard tap water? Maybe HCl? Though I am sure that using any harsh chemicals could potentially mess with sensitive seals, like on the water pump spindle or for the turbos. Maybe even mess with water temp sensors etc? Dunno...
Main risks with big overheat would be -cylinder temps causing pre ignition -warping heads/damaging head gasket -oil thinning out at temp If you’re looking for an excuse to rebuild go for it, but if it holds pressure and runs quietly you really don’t need to overthink it.... Rust has probably come out of the block or corroding pipework. It is very hard to thoroughly flush and clean the block without pulling the engine apart. Power flush is a useful tool but even then you can’t really fully drain the motor. Remove the thermostat and flush it prior to refilling.
When you say 'power flush' do you mean like a pressure washer, or an actual purpose built tool? Something like this? I actually didn't know something like this ever existed. So the whole system has never been properly flushed in the 6 years I've owned it. Hopefully I haven't already rusted out the new water pump I replaced a couple of years ago :/ I'm also tempted to take the radiator to get cleaned properly by a specialist shop. It's pretty damn brown inside...
