coolant leak

[bellis_GTR]

Yes boomer that's exactly what I'm talking about, how the f did he manage that ? I talked to Andrew and he said theres only 3 ways 1. Remove plenum 2. Hoist the car up and pull starter off 3. Pull engine.

I chose to remove the plenum, never done it before but took me about 1 hour 45 mins. It was quiet simple actually. That's with no directions or instruction so I imaging someone who has done it a few times could do it in about 1 hour or less.

How I did it? I started the job at 9am with a friend, we managed to get the bottom bolt on the starter off in a hour, then we tried the top bolt and it took forever to get that one. We used different types off tools and combos, like a short handle ratchet with a long socket or other way around. My friend ended up leaving and got my brother (15yrs) to get his little hands on the top bolt and I got the ratchet in. Finally got it. Theres a lot more to the story. I found the leak at 8pm in the rain, mind you I was working in a complex parking lot hahaha. It was a good experience tho. If this didn't happen I wouldn't of learned this much about the coolant system.

Its possible you just need patients, or you pay someone else to fix it.

My first thought was to remove the plenum but me and my friend decided to tackle it with it on first, since we thought the plenum job would be to hard.

I suggest if you ever take the engine out, Replace all the coolant and vacuum hoses. It will be worth it in the long run. Plus its not expensive for a heater hose kit.

[evilgtr]

The plenum actually wasnt to bad at all to remove, I have never taken it off before so the process was a little slower but carefully planned. Im confident now that I could do the same job start to finish in 4 hours so for those of you reading this if you have leaky coolant hoses or simply want to upgrade the hoses for peace of mind then go for it the job can be done start to finish in a day easily.

I would happily be a text or phone call away to let you know how I did it and help in anyway I could

[Arch]

I recently had this problem with mine. Turns out it was the hose above the starter engine, also discovered the intake manifold gasket was leaking and a blocked vac line. (could have been alot worse.) If you guys are in Van i recommend going to cannonball racing on south west marine drive.

[bellis_GTR]

The plenum actually wasnt to bad at all to remove, I have never taken it off before so the process was a little slower but carefully planned. Im confident now that I could do the same job start to finish in 4 hours so for those of you reading this if you have leaky coolant hoses or simply want to upgrade the hoses for peace of mind then go for it the job can be done start to finish in a day easily.

I would happily be a text or phone call away to let you know how I did it and help in anyway I could

What were the tools used? I couldn't find a combo to use with the tools I had to get underneath to the bottom bolts. Did you remove the master cylinder to get more room or anything else? I heard its a lot easier to get the back bolts.

I forget what its called but Nissan put this coating stuff on the plenum to fully seal off everything. Will I need to put this stuff back on if I remove the plenum? What about gaskets, Do they need to be changed every time you take the plenum off?

Thanks

[evilgtr]

bellis - I have no idea what coating Nissan puts on the plenum this is the first time I have ever heard of it. So Im going to say no you dont need to worry about it. As for gaskets Iv got tomei metal gaskets through out my engine so they can be re-used multiple times as long as they are handled with care. If you have the OEM gaskets then yes I would absolutly replace the plenum and throttle body gaskets.

The tools I used were 10mm and 12mm stubby and long wrenchs, 30" long needle nose pliers, special hose pliers ( lifesavers !!! ) the longest flat head screw drivers you can find, 1/4" ratchet with 3 extensions which were all different lengths, 1/4" knuckle that I attached direct to the socket for getting in the tight spaces then add extensions as needed, crazyglue for glueing the washers and nut together so you can get them on the bottom plenum bolts, a flexible magnet with light on it to pick the nuts for when you drop them - you will drop them lol, a old car speaker to magnatize the sockets for removing some of the hard to reach nuts and bolts, I think that was about it. While I had my throttle bodies off I cleaned them up ( they were pretty much spotless anyways ) I didnt re-use any of the old clamps so youll want to buy some hose clamps of various sizes, Also I bought electrical connector cleaner and cleaned all connections before aI replaced them including injector plugs.

I didnt have to remove the master cylinder,I thought about it but the work it involved wouldnt have changed anything or made the process any easier. the only difficulty I encountered were the 2 b**ch bolts. I can tell you how I removed these when the time comes - on the plus side these 2 bolts will not need to be put back in .

hope that helps.

[boomer3]

I agree with evilgtr, the best way to do this job is removal of the plenum. Once you do it 1 time, you should basically have the hang of it. It's way slower when the engine bay is cold / hoses are hard to work with.

As an update to my situation. I still haven't been able to fix my coolant leak, as it presents so randomly, i can't diagnose it when it actually presents itself. I had it up on a hoist, with the engine totally warm, and fully pressurized and of course it wouldn't leak for me lol. Now my car has decided to start missing really badly when it's cold, sounds like its running on 4 or 5 cylinders until it warms up. I'm going to hedge my bets either on coils or 02 sensor....

[bellis_GTR]

Thanks evilgtr that should help. I made sure to have a flexible magnet, I dont know how many times iv dropped washers, bolts, sockets and the magnet has helped every time. Ill attempt to take the plenum off this week or so. It would be great to keep the engine in and change all the hoses.

boomer3- I found when my coolant leak started it would come and go. I noticed later on that when I part on uneven road or a little hill it would leak every time no matter what. But when I parked on even road it never did. Whats the status on the hoses that are in there now? Are they all OEM? When I finally got to my hose I think I was to excited to see it run again and might have tightened the clamps to tight.

Also what thermostat do you have in there? What temp does it open?

[evilgtr]

Boomer what kind of Rad are you running ? Oem ? What is the release pressure on your rad cap ?

[bellis_GTR]

Boomer what kind of Rad are you running ? Oem ? What is the release pressure on your rad cap ?

Ahhhh Another thing I forgot to mention! I forgot to ask what evilgtr said.

When I first got my GTR I had little coolant and over heating problems. I saw that I had a 13psi rad cap on a stock rad. Then I thought maybe this is the reason. I thought all "Imports" usually run a higher pressure rad cap rather than "Domestic" run lower pressure. So I changed mine to a 16psi or 1.1 bar and thats when sh*t hit the fan lol. Back then I didnt know this will cause abnormal pressure. I learned the hard way.

[nelsonmxmarc]

Ahhhh Another thing I forgot to mention! I forgot to ask what evilgtr said.

When I first got my GTR I had little coolant and over heating problems. I saw that I had a 13psi rad cap on a stock rad. Then I thought maybe this is the reason. I thought all "Imports" usually run a higher pressure rad cap rather than "Domestic" run lower pressure. So I changed mine to a 16psi or 1.1 bar and thats when sh*t hit the fan lol. Back then I didnt know this will cause abnormal pressure. I learned the hard way.

Hmm well i guess that settles my issue then.. Nismo rad cap will have to wait for new rad.. lol

[boomer3]

Boomer what kind of Rad are you running ? Oem ? What is the release pressure on your rad cap ?

I'm running a nismo cap (1.1 bar i think), and I believe it's a stock rad. This could be contributing I suppose. Also, it's a higher temp thermostat then factory as far as I know. It's sitting about an 1/8th above half heat. I wouldn't be suprised to find i'd tightened one of the outer most heater core hose a little too much in my rush to put it back together, but like I said, it's so hard to figure it out when it randomly leaks. It sometimes won't leak at all, and 1 or 2 times, i've found it leaking significantly! One thought I had was that the thermostat has stuck shut once or twice, causing the heat to go above normal and letting the pressure rise just enough for it to leak where I over tightened a hose. Does this sound plausable guys?

[evilgtr]

Ahhhhhh get those high pressure rad caps off hahaha I have one but I'm running a blitz race rad. If you have a intermittent leak I would bet with almost %100 certainty it occurs only when the engine heats up to much and the rubber softens up and reveals the split of when the engine is not warm enough so the thermostat isnt open so there is more pressure on the hoses. Put the oem cap back on as this is the low pressure cap that was designed to be used with the oem rad. It provides the weak spot in the entire system to relieve excess pressure to prevent hoses blowing out.

I would bet with a low pressure rad cap your leaks you have wont show themselves anymore.

Boomer your theory is solid and my suggestion to you is replace your thermostat with a 60 degree Nismo item, I believe they are about $75 (I can't remember what mine cost) because it opens cooler you will have lower temps and lower pressure like you mentioned above - and it's a simple install.

Worth a shot right ?

[boomer3]

Totally worth a shot. I will get on this right away. I'd rather change up the thermostat and rad cap, then have to take the plenum off again with the possibility of no success!

Unfortunately I don't have the orignal rad cap. What are the chances that a 240sx would share the same rad cap? Ie so I can grab a 0.9 bar cap at crappy tire. I guess I could take the nismo cap in and see if one matches up..

Thanks for commenting in on my leak theories evilgtr, it's a huge help.

[evilgtr]

hey no worries at all, I would go to canadian tire or parts source and pick one up for $10. just get the oem spec or a low pressure cap and your good to go