hot or not?

Hello everyone, i have a 1989 90, when starting the engine is takes about 5 minutes for hot air to blow through the heater, about 2 miles down the road my temp gauge on the dash goes up into the red, i have replaced the coolant and the thermostat,and there are no air locks, the top rad hose is warm/hot but the bottom hose is cold and the coolant in expansion tank is cold, the engine block is hot to touch and so is the thermostat housing, the thing is it doesn't boil even though the gauge is in mid red, really don't know whats going on!! i don't know if theres a blockage somewhere or what, i flushed the rad and clean water came out. situation no change, when getting rid of the air lock i jacked the rear of the car up for the bubble to move. help help !!

Check the temp gauge is not faulty or got a bad earth. also check the temp sender in the thermostat housing put a new one in and see if any difference.

cheers mate il give it a bash

I'd say it's an electrical issue, bottom hose cold cos that thermostat hasn't opened and it hasn't warmed up properley after a 5 minute journey, if the engine was that hot you'd barely be able to touch it and air coming through the heater ducts would be red hot.

is the same symptoms after an hour journey, cold bottom hose and cold coolant in expansion tank

what would i do about electrical issue, which earth could be at fault?

Try it with the thermostat taken out and while it's out test it in boiling water

will do mate cheers il try it tomorrow

Mine was the water pump, had a cheep plastic one in it,

Doesn't the temperature gauge get 12v ignition live via the green wire and variable ground via the wire leading to the sender? Shouldn't be a ground other than the one feeding the bulb.

Disconnect the sender wire and check the gauge. Stick a rivet into the terminal of the sender wire and touch against the engine, the needle should go full on. Only problem with electrics other than that would be if the green wire was being pulled low by a dodgy component but you would see issues with the fuel gauge and countless other circuits.

If you've changed the sender already the next job is to check the sender wire.... Crimp a red bullet terminal to the end of some 1mm2 electrical wire 4-5 metres in length. Push the red crimp over the senders centre pin and feed the end of the wire out through the gap in the edge of the bonnet and in through the door then connect this to the sender wire connection of the temp gauge. Now try it..... If it does the same as it did before then you have tested and ruled out the sender wire leaving the gauge as most likely culprit IF however the gauge now works correctly you have a damaged sender wire so feed the temporary wire to the gauge by a more permanent route and snip off the old wire at each end.

The entire temp sender circuit only consists of gauge fed from ignition live and sender wire which goes to sender and this takes ground from the engine ground. How is your engine ground?? If it is dodgy then it could be an issue but is easy to test, attach a jump lead to the engine and to a ground point (easy one is to get two 3m jump leads and connect them to each other creating a 6m lead then connect one end to the neg on battery and the other to the engine..... Again, if this fixes the problem you have your cause so replace this with a fresh earth strap from engine to chassis.

Not neccessarily a good test with the stat removed, iirc when the stat opens another part of the stat shuts of another waterway, which again iirc ss the bypass hose, the little one from the drives side of the stat housing down to the water pump

it seems that the coolant is hot from the top hose to the thermostat, and just past the thermostat the coolant is hot to the water pump but after that it gets cold... does this mean its a broken water pump?

turns out someone had put the wrong thermostat in... and me being an idiot didn't realise that it was wrong, it didn't have the spring and extra plate and when i tested it it didn't do anything in hot water, neither did the one before that, euro car parts have got the wrong thermostat on the system for my reg,

problem still not solved, every time there is a thermostat in the car it overheats!!! ran it without the thermostat, all pipes got warm inc expansion tank, gauge just under half, put new stat back in and gauge goes back up to red!!! what the hecks going on, starting to think something might be missing in the housing?!? surely can't have had 3 duff stats...

I know it might sound stupid and I'm sure someone will be along to shoot me down but are you putting it in the correct way up?

does it not only go in one way ? on a 19j

I don't think you can put it in wrong. Spring should be on the bottom side. Stat could still be sticky. I had one that opened but it was inconsistent and opened at too high temp. I don't think it's a good/valid test running without the stat as it won't be closing off the bypass hose.

On my 200 TDI, the water in the expansion tank does not get hot. I don't see why it should as there will be no circulation in that area - sure over time, hot/warm water may displace through thermo convection or whaterver it's called but it should not be hot unless the engine is working very hard over a long time. Last weekend I did a 200 mile round trip on the motorway, towing a trailer on the way back. I was checked my water level 4 times on route as my water pump was dripping and the expansion tank was never more than midly warm. The gauge read 89 degrees all the way, dropping to around 80 in 30 zones.

Ignoring the gauge for a moment, are you sure that your engine is too hot? You can get an infrared hand held stat online for about £10. Might be worth getting one and verifying the temp of the head, top hose etc.

As a very rough guide, once the engine is well warmed, the top hose should be too hot to hold. The rad should be too hot to hold and the temp should drop of drastically towards the bottom. The bottom hose should be cool or warm, but not hot, unless you are working the bollocks off your engine.

cheers mate, i know the gauge is reading correct as i can smell a burning engine in the cab also the heater blows red hot air....although the coolant doesn't boil the top hose is very hot all the way to thermostat housing then stone cold after that and the head is red hot, it has to be the **** stats from euro car parts, testing them in a kettle and they are opening far too late and only open sometimes and aren't very consistent, do you think buying a 74 degrees one would be better ? if my engine runs hot a lower temp stat surely would help, is there any decent stats out there that won't stick>?

I don't know who makes decent stats. I think your best bet would be to ring an independent or stockist and ask which makes they recommend, then post the info here as I was asking the same question recently

I had the same issue with my new stat, it was sticking and I went back to using my old stat which worked perfectly!

Don't substitute it for a lower temp one, you just need one that opens at the design temp (88 for 200 TDI, not sure on 19J). Opening too soon will use more fuel and premature wear.

cheers mate will stick to an 82 one ! the best ones I've seen actually say wax stat on the top of them