MOOSEcannoN

Hi everyone
I'm new to the forums (signed up a while ago but forgot to post).
I love cars and I know a bit about them 'in theory', but other than that am not too car savvy

I've recently got my hands on a 1987 U12 4WD bluebird with an SR20DE for my daily driver while my sr20de powered ae86 is in the shop.
Here she is:


I got her really cheap because the engine was buggered, I got a friend to help me replace the engine with one from a 4WD U13 (engine was hard to find in 4WD).

Now that I've been running the "new" engine for a while now I've noticed a lot of corrosion in the cooling system, there was plenty of anti-freeze in there but has now turned brown and there is brown foam in the cooling reservoir, I've done some research and hear this means there's oil in the cooling system due to a leak in a gasket somewhere. When revving the engine with the radiator cap off the water doesn't gush out, it just overflows a little. I don't think it over heats but the temp gauge only works on some occasions, I believe this is due to the car not having a thermostat. The car uses barely any oil if any, same with the water.

Is this something to worry about? what do you recommend I should do? I don't really want to spend too much money as its just a run-about car, I'd rather spend the cash on the ae86.

UI8281

if I remember correctly the coolant shouldn't go brown because the sr20 is an alloy motor. But you can get a test done at some places that chemically test for exhaust fumes in the coolant. I would suggest getting that done to make sure your head gasket is sweet. The brown stuff could be stuff out of the radiator or crap that could have gotten into the motor if it was sitting before it was installed.

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N14 chassis + N15 Autech sr20de = Hybrid

MOOSEcannoN

Thanks UI8281

I'm hoping its corrosion from when the engine was sitting prior to it being installed. I took off the overflow pipe which leads to the reservoir and there was a lot of corrosion stuck to the walls of the pipe so the corrosion could have been there before the new engine. Do you suggest giving it a flush and see if the corrosion returns? I heard that it might not be a good idea because it could free some corrosion that's filling a gap in the gasket if there is one ? is this a valid opinion ?

UI8281

Yea I'm sure you would have problems if the headgasket was busted. Like over heating. I'm guessing you have checked the oil for milky-ness. I suggest giving it a flush and make sure you refill it with coolant that has a rust inhibitor in it (I think most of them do) and also make sure you bleed it well with the bleed screw that's next to the thermostat and the one on the heater hose. And possibly replace your coolant temp sender if the temp gauge is playing up. I just replaced mine because my gauge was laggy.

UI8281

And if you do somehow manage to loosen corrosion thats holding the headgasket together you will just find your problem of a blown headgasket sooner, and possibly finding it while at home rather than finding the problem out on a long drive.

MOOSEcannoN

wow thanks thats really helpful. I did change the oil about 3,000km ago, I didn't inspect the oil for milkiness.. I'll get a friend to help me bleed the cooling system then refill her with anti-freeze. I think i'll do a proper flush after the long drive, just incase some corrosion is lifted and creates a gap. where abouts do I find the coolant temp sender? the temp gauge just sits on cold, very rarely it moves to a quarter or half way. thanks again for your advice

UI8281

I got my sender from Appco a couple of weeks ago and it was $29 I think. it is a bitch to replace though. The sender itself is in a pipe on the back of the block under the inlet manifold. I have found that you can either take off the inlet manifold runners (the top section) or the brake master cylinder. And then you will see the pipe with two sensors in it, one is the coolant sensor for the ecu and the other (smaller one, one wire) is the temp sender for the dash. You could also replace the other sensor while you're there but if the fans are coming on etc it should be sweet. If you changed the oil and it was milky I would say you would definitely notice it. Also putting a thermostat into it could be a good idea. And a tip with bleeding the coolant with the heater hose bleed bit is you take off the little rubber cap and then squeeze a radiator hose until coolant comes out and hold it there while someone else puts the cap back on.

good luck with it all and if you have any problems with the sender I can take some photos of where it's located etc.

MOOSEcannoN

Cheers UI8 You've been really helpful. I'll give her a bleed today, will have a go at replacing the sensor next week and let you know how I go

MOOSEcannoN

have replaced the coolant and taken it for a nice long trip, coolant is still green no problems The temperature guage is still not working though, does this mean that the radiator fans won't turn on because it doesn't know the engine is hot? I've never noticed the radiator fans ever being on, I tried having a look behind the intake manifold, there were a couple of wires leading underneath the manifold where I couldn't see, one of the wires had a plug on it which if I unplugged the car wouldn't start, so I'm guessing that's not it? lol

here's a pic with the plug disconnected



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UI8281

Yea that plug is the starter motor trigger wire. The fans should turn on because the coolant temp sensor for the ecu is not the same sensor as the one for the dash. Do you still have the old motor out of this car? and what ecu are you using on this motor? I have been told that the ecu temp sensor should match the ecu and the coolant temp sensor for the dash should match the car. Did you replace the thermostat when you put the new coolant in?

To see the sensors that I'm talking about you have to look down under the end of the intake runner for number 1 cylinder. kind of behind the oil filter and next to the brake master cylinder. it will be 2 sensors screwed into a steel pipe. I will hunt around for a pic of it.

UI8281

Ok so I couldn't find any photos so I went outside and took some of mine. In the first photo you can see the red plug, that is the sensor for the ecu. Next to that is the sensor for the dash. It's just out of view but you can see the black wire running to it, and photo 2 is to show you how much of a prick it is to get to them.

MOOSEcannoN

ahhh I see, thanks for the pics, its dark at the moment but will have a look tomorrow. I dont have the old engine but as far as I know the sensors are from the U13 engine that's in it now and pretty sure the ECU is from the U12 engine. I didn't replace the thermostat when I flushed the coolant because I didn't know where to look for it lol
How can I check that the radiator fans actually are coming on?

I can't afford to take the car to the shop unfortunately

UI8281

Haha I know how you feel, not wanting to pay mechanics bills. You can test the radiator fans by heating the car up and just see if they flick on but if you are concerned about it you can see if the fans actually work by pulling the red plug off the ecu coolant sensor, this will put the ecu into a mode that protects the motor from over heating and because it can't get a signal from the sensor the fans will stay on all the time. But your ecu will show a check engine light. but without a thermostat in there the car most likely isn't getting hot enough to run the fans. The thermostat is under the thermostat housing which is where the lower (longer) radiator hose goes back into the motor. Where in NZ are you. If you were in CHCH I would be happy to show you everything one day.

MOOSEcannoN

thanks for the offer thats wicked, I'm up in the far north (Whangarei). Drove down to Auckland today, temp guage didn't work the whole time, when I got to my destination I hopped out and I fiddled with the dash sensor wire, turned the engine back on and the temp gauge started working so could just be a dodgy connection/plug. I left the engine running for about a minute and the radiator fans turned on as well

couldn't get the ecu plug off 'cause it's annoying to get at lol but know it works now so that's cool. How hard is it to install a thermostat?

UI8281

Oh that's good news. It definitely sounds like a connection error to the sensor then if the gauge worked, i have heard of some people soldering that wire onto the sensor so they don't have that problem. or you can crimp a new spade terminal onto that wire. And that's wicked as that your fans turn on, now you can rest easy knowing that it's not going to overheat while sitting there. And as for the thermostat it's quite easy, i'm planning on re-sealing my thermostat housing this weekend so i can take pics for you. You will just need a thermostat and some gasket goo/maker/rtv silicon.

MOOSEcannoN

pics would be awesome thanks for all your help I really appreciate it, I've learned heaps and it's saved me paying a mechanic to figure out the problem!

UI8281

Haha no problem. I will most likely take some pics tomorrow when I put the car in the shed, but right now it's beer o'clock!! I myself have learnt so much off online forums and have saved myself thousands.

MOOSEcannoN

awesome, temp guage is working pretty much all the time now. Unfortunately she's developed a missfire, it's happening a lot mostly under load I think. When i got a wheel alignment a while ago they guys there told me it could do with the timing adjusted to produce more power, would this have anything to do with the miss? At home I've got a spare pair of leads I can try and I'll check my plugs as well (not at home atm).

UI8281

that's good then. I didn't get a chance to work on my car in the weekend so couldn't take any photos of the thermostat. Is the misfire a proper misfire like the car is jerking under load or is it detonating/pinging? If your spark timing is too advanced you will get detonation which will kill your motor.

MOOSEcannoN

it started off as a proper misfire like the car jerking under load at about 2-3 grand, had been doing that rarely, then recently got worse this weekend, sometimes it felt like I had no power but the car wasn't jerking, sometimes it feels fine.