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1990 Nissan D21 thermostat problem


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monsiep
User

Jan 21, 2018, 6:44 AM

Post #1 of 12 (514 views)
1990 Nissan D21 thermostat problem Sign In

Hello, I bought this old Nissan a couple of years and it had a broken radiator. At the time someone told me it might be the thermostat so i tried to replace it but when i followed the upper hose I found no thermostat or housing. That same person then told me maybe they took the thermostat out so I kinda said meh and left it and replaced the radiator and it never bothered me because I was in a warm climate. Now I'm back in the cold and am looking to replace it and I noticed what looks to be the thermostat housing connected to the lower radiator hose. Is it possible someone switched them up? Or is this just the way it is on this vehicle. Any help would be greatly appreciated. Thank you.

https://imgur.com/a/8u8ue
https://imgur.com/a/iRT6M

I took some pictures in haste before running out. I can take more if necessary. The second picture is of the suspected thermostat housing. The first is of the setup. The upper house goes directly into the engine there's no spot the thermostat could fit that I can see.


(This post was edited by monsiep on Jan 21, 2018, 6:51 AM)


Tom Greenleaf
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Jan 21, 2018, 9:27 AM

Post #2 of 12 (491 views)
Re: 1990 Nissan D21 thermostat problem Sign In

2 engines available sport, which one? The 2.4 cyl. one should look and be available like this housing and all. Trouble is this is both old and studs probably but any way it's fastened to engine right where upper radiator hose attaches will be a corrosion battle and risk breaking things over a guess that this is the problem at all. You can test it without touching them and suggest you do first,
Items look like this..........

You'll need a new gasket and scrape old one off or out as needed,


T



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jan 21, 2018, 9:35 AM

Post #3 of 12 (487 views)
Re: 1990 Nissan D21 thermostat problem Sign In

Sorry for two posts in case you already read the first. Your pictures aren't even of a thermostat area! This is generic and the most common way to do one in as short of a video as I could just find,


> https://www.bing.com/...amp;&FORM=VDRVRV <
Good luck. Trouble is you may not need it as said and bust stuff up trying,


T



monsiep
User

Jan 21, 2018, 10:46 AM

Post #4 of 12 (477 views)
Re: 1990 Nissan D21 thermostat problem Sign In

Okay yeah that's the housing I'm talking about just my photo is a terrible angle. I already have the gasket. I guess my question is as it's set up now the lower radiator hose runs to the thermostat. Shouldn't it be the upper radiator hose that connects to it just like in the video?

Thanks for the response.


Tom Greenleaf
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Jan 21, 2018, 11:25 AM

Post #5 of 12 (473 views)
Re: 1990 Nissan D21 thermostat problem Sign In

You still didn't say which of 2 engines possible? No matter if you want to check this you could with an infrared, touchless thermometer or your hands most of the time. From cold feel the neck or hose near what was shown starting from a totally cold engine. Now just wait a few minutes it should STAY cold, eh, might move up away towards radiator and feel there for temp full circle of the hose not sure what angle it might be on?


When it reaches its rating for full temp marked on thermostats always should use what manufacturer suggested new nothing lower unless it's listed as correct OE as if truck was new.
If it waits then slowly warms up it's almost certain that isn't the problem. Other reasons for total confusion with cooling temp anything is it leaks, can't hold pressure or system is low must be known and you'll need to know how to fill a system such that no air is inside the pressured up side of the system when warm. If no pressure ever stop this and find where it's leaking may even be a radiator cap.


If you insist on doing this keep that video and watch the next as well is longer. You may need a gasket scraper and a tool to remove hose if really stuck on the neck. Right now even if you don't take this on put some PB solvent on a Q-Tip and soak the threads of nuts, bolts that hold housing onto engine.
What was shown was about $32 bucks and NOT available at Autozone I used for the picture - didn't know which engine and they can be wrong or others.
Make sure if doing this thermostat if possible to install upside down isn't! If this mounts to the side you either use just some "Form-a-Gasket" by Permatex to glue it in place if it falls crooked will just flow all the time or leak. Other is use fine wire used commonly for flower arrangements or just real fine wire you can loop the thermostat running wire up to end of upright metal housings and bend it such that it can't move while installing quickly so nothing goes out of place. The wire used should be able to pull out cleanly if you follow me on that?
I'll save how to fill the dang system or end up writing 5 pages here. See if it works first but you must also know system is full and can hold pressure or wait to mess with this. Temp by infrared thermos shouldn't really ever exceed the rating of the thermostat that's inside there now once up to full temp on a RWD belt driven fan type engine or there's more to figure out/diagnose what is wrong.
Up to you. This is either simple as it gets for an experienced tech or a wild bitch busting stuff and really making troubles you don't have now,


T



Hammer Time
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Jan 21, 2018, 6:38 PM

Post #6 of 12 (460 views)
Re: 1990 Nissan D21 thermostat problem Sign In


Quote
I guess my question is as it's set up now the lower radiator hose runs to the thermostat. Shouldn't it be the upper radiator hose that connects to it just like in the video?


No, many cars put them in the return hose, especially Japanese cars.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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Jan 22, 2018, 2:17 AM

Post #7 of 12 (453 views)
Re: 1990 Nissan D21 thermostat problem Sign In

Yes - can be and use the type thermostat used to direct the temperature to it. Everything is on a hunch with this maybe just let a real mechanic suggest what you need in person is the best thing to do. Old as it is you are losing some exact web info and beginning to make parts harder to find or wait for them. Find engine size is primal of course. IDK, one of these around those years used 2 spark plugs per cylinder on the 4 cyl as I recall on opposite sides of the engine. VIN # is telling of just what this is if not altered?


T



monsiep
User

Feb 20, 2018, 6:14 AM

Post #8 of 12 (392 views)
Re: 1990 Nissan D21 thermostat problem Sign In

Update:
So it turned into a bit of a nightmare. I ended up breaking the housing by overtightening and so after getting the new part and putting it all back together, there is the tiniest leak coming from the gasket like if I stare at it I don't see it but if i go away and come back a tiny drop will have formed. So I started it up it's and solved my problem. Guy at work told me the old thermostat was stuck open. And it kind of worked out that the housing broke because when I removed it it was heavily corroded inside the hose.

So anyway i decided to celebrate by learning how to diagnose a faulty thermostat so next time I didn't just jump headlong into uncertainty and I gave one of the hoses a little squeeze and boom pinhole leak.

So my question is to regarding the gasket I ordered a second gasket in case I F**ked up so I have the option are to show up at the mechanic and have him unF**k it. But really if I can get away with a tiny drip of a leak I'm happy. What are the potential consequences of this. Will one of those radiator sealing products help me at all? Im replacing the radiator hose regardless.


Hammer Time
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Feb 20, 2018, 6:29 AM

Post #9 of 12 (390 views)
Re: 1990 Nissan D21 thermostat problem Sign In

Potential consequences? ..................... blown motor maybe, definitely can cause some severe damage.

If you are going to try to do you own repairs, you have to own and repair your mistakes. You likely broke the housing because the thermostat was not positioned in it's groove properly. You need to replace the broken housing and fix the problem right or simply pay the mechanic to do it right in the first place.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



monsiep
User

Feb 21, 2018, 8:57 AM

Post #10 of 12 (364 views)
Re: 1990 Nissan D21 thermostat problem Sign In

I understand that I am confusing.
1) I broke the housing because i had it seated wrong and when i added fluid and it leaked i instinctively tightened then pop. (It cracked at the bolt)
2)replaced housing
3) replaced pinholed radiator hose

Existing problem: Small almost unobservable leak coming from gasket

Question: can I get away with it?

Also, for understanding. If the answer is no could it be explained why. I'm sitting here trying to see how a small leak may cause engine failure. Is it because it would allow air into the system?

When I changed the rad about 2 years ago the Haynes manual didn't tell me about burping the cooling system and this time I read something about it from another source so I did it. I'm wondering if I just got lucky running with an air saturated system for so long. I'm sure there's something I'm missing.


Hammer Time
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Feb 21, 2018, 9:40 AM

Post #11 of 12 (360 views)
Re: 1990 Nissan D21 thermostat problem Sign In

It shouldn't require an explanation of why a coolant leak of any kind can lead to engine failure.

Coolant loss leads to air pockets. Air pockets cause hot spots. Hot spots damage motors.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Feb 21, 2018, 9:46 AM

Post #12 of 12 (360 views)
Re: 1990 Nissan D21 thermostat problem Sign In

Arggh: Is this leak right at a fairly plain gasket at housing like just cardboard? They might seep and seal quickly usually if so. You should be working with a pressure tester before you even add coolant see if system is holding air which would leak a lot more easily than liquids. Spray areas you don't trust with just light soapy water they'll foam or large bubbles a problem either decide to fill or go back.


Thermostat if side mounted should be indexed for top of it. It has to stay in place or the job fails, leaks. IDK - tricky ones I'll use a smear of gasket maker till those are stuck or a fine wire to hold in housing till all tightened up.


If it holds pressured air then fill proper mix near always 50/50 antifreeze and water. Run engine and heater till it should push thru any air and there will be some you allow it to cool and check at radiator cap once or twice cycling this way before sure it's full.


System HAS to hold pressure check that it does and the item it the pressure cap that allows that. A pressure tester should test the cap as well. If already mostly warmed up more pressure quickly not very fast check again later it can on it's own.


Why - anything will have spots or intended above boiling point without pressure which gives you 3F more degrees before boiling per pound of pressure of the proper pressure cap.


Guess what I'm saying is while you are getting in all kinds of trouble over a thermostat you should have a pressure tester and check for active leaks and why lots faster when it's just air as said,


T







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