about a month ago (i think) i took the children and me mrs over to a friends house who i hadn't seen in ages, when i pulled onto his drive the temp gauge on my zed shot up to the redzone, i switched the engine off and could hear the water boiling and being forced into the overflow bottle.

 

Got out of the car and looked, sure enough the overflow was emptying all over his nice clean drive. so had to get the car towed back home.

 

When i finally got the chance to go over it, i refilled the rad and warmed the car up, she started over heating again, not rapidly but enough to know that it wasn't going to stop once it got to 100c, so i switched the engine off, and checked the rad, cold at the top and bottom.

 

Having a spare thermos in the garage, i went and tested it to make sure it was ok. (to test a thermos stat, boil the kettle and stick the thermos in a point glass, carefully poor the hot water into the pint glass - not too quickly or you could shatter the glass - and watch to see how much and how fast the thermos opens)

 

Having tested the replacement thermostat and happy with it, i drained the car and took the pipe off housing the thermostat, and went and checked the old one, sure enough the thermostat had failed it would only partly open.

 

so changed the thermostat, refitted the water pipe, and filled the system up again. anyway, test time, engine came up to temp and all seemed good, thermostat opened and the rad filled with hot water, on idle all seemed good so i bleed the air out of the system and took her for a test drive. she started over heating again, so i pulled over and noticed steam coming from under the bonnet at the battery area, popped the hood, i had blown the by pass pipe off the turbo, so quickly refitted it and limped her home.

 

I then changed the pipe and put a better clip on it. refilled the system and took her back out for another test drive after id got her up to temp while sitting there idling. still overheating.

 

As i had a strange rattle from my water pump when i replaced the engine, i went and dug the new water pump out of the garage and changed that with the help of steams who popped over.

 

Again i refilled the system and bleed it, it still over heated when driving on either a duel carriageway, or motor way, but not when driving at 30mph in residential areas.

 

Next up was the timing, when jeff did my timing at JAE, we got it to 15 BTDC yet the CAS unit was all the way over, thinking that that couldn't be right, i remember that i changed the ECU for one i took of my black breaker ages ago that was a UK spec auto, same as my car. the ECU i took out was for a Japspec auto chipped and mapped for higher boost on stock injectors, i changed the ECU over when i had gear box issues.

 

Anyway, i noticed when i put the old ECU back in, the timing needed changing again, so out came the timing gun, got the car up to temp and checked, 30 on the crank pulley mark. adjusted the CAS unit accordingly which in turn brought the CAS back to sitting almost dead center on the retaining nuts and showing 15 btdc, this also cleared up my mysterious misfire on idle.

 

car was running a lot smoother then, so think the UK spec ecu was giving false readings.

 

took the car out for another test to see what was going on, driving around town everything is fine, the moment you get it on a motorway the temp starts creeping up again, Ive tested the rad cap and that seems to be leaking Air into the overflow.

 

Current status of the car is, im no longer drinking coolant (though i think that was airlocks to be more honest) as i can no longer put any more coolant mixture in, if the car is sat still she doesnt over heat, when driving i have to have the heater on 35 with hot air blowing out (and its very hot air) or the car starts to over heat, if i pull up at traffic lights, sometimes the heater starts blowing cold air and the temp starts to raise, the moment i give it 1500 revs, i get hot air again and the temp starts coming back down.

 

So far the car will stay at around 82 to 85 degrees (nissan data scan) when i get cold air on my heater set at 35, the temp creeps up to around 95 97, if i join a motor way and cruse at 60 the car will sit at around 92, but the moment i come off the motor way and start town driving, the temp will sore to around 117. which isn't good, the electric fan will be on at this point, and if i pull over, she will slowly go back down to around 86 as long as i have the heater on.

 

The only parts i haven't changed on the cooling system is the radiator or the rad cap. though i do need to change the rad cap as its not holding pressure which i think may be adding to the problems.

 

Other than the radcap, the only thing i can think of that is causing my over heating is a clogged radiator. it no longer over heats rapidly, i have no strange smell coming from my tailpipes, im not loosing coolant, changed the thermostat and water pump, replaced both by pass pipes, checked rad cap that seems to be leaking air into the overflow. and all this from a failed thermostat. i have no mayo in my coolant and none in my engine oil.

 

(if you want to test if your cap is holding pressure, with the engine running and up to temp, remove the overflow pipe off the radiator near the cap, and put some spit over it, if it blows bubbles at you, then its not holding pressure)

 

(there ya go groover, i heard you missed my essays:lol:)

Edited November 25, 201114 yr by vodkashots

It sounds to me like a water circulation problem, whether that is caused by the pump, a blockage or by an airlock it's difficult to tell.

It sounds to me like a water circulation problem, whether that is caused by the pump, a blockage or by an airlock it's difficult to tell.

 

from what zerocooldel told me, the engine had been sat for about a year, as i thought the same, another reason i changed the water pump as i thought the fins on it had corroded, with one of the engines i have in the garage, where the thermostat has been removed, its built up like a layer of rust covering the top of the water, bit like ice but rust instead.

 

Need to get a new radiator i think and give the whole system a good flush. does anyone know the best way of doing this?

 

Andy, the ECU ive got thats chipped and socketed has your name on it? did you used to chip and socket them?

Do know much about temp stats but good to have you back on with your essay type posts !:thumbup::bow::bow:

 

I did miss them !

Had something similar before was a blockage in the heater matrix, restricting flow, get some collant flush in there and see if that helps then bleed and refill with good stuff.

Edited November 25, 201114 yr by ZX-TT

Do u have the viscous fan or electric fan?

 

Alz.

Andy, the ECU ive got thats chipped and socketed has your name on it? did you used to chip and socket them?

 

I have socketed dozens and dozens of them, both for individuals and for some traders as part of their services.

Do u have the viscous fan or electric fan?

 

Alz.

 

i have the viscous, (also the electric thats mounted on the front of the A/C rad) ive already changed the clutch to see if that was the issue, i also have the shroud on and inplace, both top and bottom parts.

 

Im thinking its more radiator orientated and rad cap than anything else. ive pretty much changed everything. the rad also came off my black zed as the one originally on my blue one had a leak after id changed the engine. so ended up putting the other rad on, that had sat dry in my garage for a good year.

Id be looking at head gasket with those problems,get a sniffer test done.Sounds like under light load its ok but pressurising under boost.

Id be looking at head gasket with those problems,get a sniffer test done.Sounds like under light load its ok but pressurising under boost.

 

im not boosting, jeff said it may be warped heads, but in all honesty everything ive read about over heating, if its HG then it usually over heats rapidly.

 

Even when i did boost, the temp still only crept up slowly rather than quickly and im not losing coolant? which i would of thought i would if i was leaking combustion gases into the cylinders

 

really hope its not HG though. other wise i may as well just break the car.

 

Seems more a cooling issue though as its not a rapid climb in heat, its a slow steady one, are there any home HG fail test kits out there to test it your self?

May be just a poor circulation problem, I have recently ran a couple of bottles of flusher through mine (for approximately 100 miles) and although I did not have a temperature issue, I was still surprised how much sediment came out.

http://www.ebay.co.uk/itm/WYNNS-CAR-RADIATOR-FLUSH-325-ML-/290555258112?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43a6716500

It did take several coolant changes mind you to eventually clear the system before putting an antifreeze mix in.

Cheep starting point?

well i suppose you need to go through a list really.

;coolant system circulation, you know the pumps good but with the crap flaoting about, you where talking about we dont know if the system has become blocked. a blocked rad will so cause issues.

;i would agree with your thoery on the whole over heating via headgaskets, however like jimmer said if its a slight leak it will only leak and pressuirise the system when the engine is under load whic explains your higher speed issues.

youve checked the thermostat and the pressure. i think a sniffer test is due this can be purchased cheaply and they are simple to use, they change colour when they detect excess co2 which indicats exhaust gases leaking into the coolant system. this would also tend to blow water pipes like the small ones at the back of the block etc. you could also do compression and leakdown tests, sure you could borrow the equipment. try for starters running a hose through the rad see how much and how quickly it comes out. these standard rads are classic for blocking up and they werent much cop when it worked properly.

process of elimination buddy.

Ive still got the rad from the last Zed if you want it mate?

Ive still got the rad from the last Zed if you want it mate?

 

thats a manual rad, id need the auto one as its got the oil cooler for the gearbox in side it.

 

Though, i still haven't fitted the manual box yet as want to get a new clutch and need to get the braided clutch lines as well yet.

its really simple to get rid of the cooler in the rad ian, just connect up a uk spec oil cooler. could even just pass it through some copper pipe temporaliy to test.

It is a Uk car mate.