Big_Mark Posted February 22, 2023 Share Posted February 22, 2023 It seems odd that you would have so many defective radiators, I know you're discouraged enough but if you have a bad head gasket blow by could be sending pressure into your cooling system, causing the radiators to fail. You indicated there is a lot of oil coming from your engine, this can also be a sign of blow by (more likely rings than radiator for oil). Sorry to add more to the pile. Link to comment Share on other sites More sharing options...
gogmorgo Posted February 22, 2023 Share Posted February 22, 2023 Unless you’ve got a rad cap that’s not doing its job I wouldn’t worry about head gasket. You’re not going to overpressure the cooling system if the pressure can get out somewhere. Take it one issue at a time. Link to comment Share on other sites More sharing options...
coheed Posted February 22, 2023 Share Posted February 22, 2023 As others have said, back off and think about how future you would feel about letting the truck go. There were many times I thought about selling my grandad's MJ, what with frame warping, title issues, and rust. Eventually I turned into a trailer, and now I still have a cool thing that has sentimental value. I'm also very glad I didn't sell it. My current truck has just been sitting for a while and only going to the dump on occasion. The front axle u joints are bad. Like missing all the needle bearings bad. But I don't wanna spend the money on swapping them because I plan to throw in the 4.10 axles from my old truck. But I don't want to do that unless I have all the parts to do the larger lift. Measuring my ride height the other day it's sitting at factory height with a Chevy drop shackle, so I don't think it'd be worth it to try the AAL I've got. So I need money for new springs. Stuff on project vehicles adds up really fast and can get overwhelming. But making decisions in the moment that future you would be disappointed by sucks way worse. Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 22, 2023 Author Share Posted February 22, 2023 Oh I am. I'm going to just stop driving it a bit and just think. Like I said I just feel kinda dumb for sitting here telling people "oh yeah I have a open cooling system" when in reality I don't. So what I am thinking I'm going to do is do exactly what Johnny Cash did. One peice at a time. When I get my car back I'll go to autozone, advance auto and pick the stuff the conversion calls for. The napa radiator I currently have costed my just over $300. I was online looking at parts and the rad I posted above was like 152, the radiator cap with the temp gage was like 40-50 and the hoses were dirt cheap, connectors too. While I'm also out I'll pick up a valve cover gasket since it does leak from the top of the motor on my driver side. I do believe those have rubber but I heard somewhere they had aluminum ones? Are those any good? I had a good sleep last night and have really thought about it and if I can just accumulate the parts overtime it'll get me ready (I think) to get the job done and get my truck right. Are valve conver gaskets hard to change? Is there anything that could go super wrong? Does the bolts have to be torqued to factory spec or do they just have to be "tight"? Link to comment Share on other sites More sharing options...
acfortier Posted February 22, 2023 Share Posted February 22, 2023 You should be able to return those radiators that are leaking, no? I would think the best valve cover gasket to get would be the Felpro one: https://www.amazon.com/Fel-Pro-VS-50522-Valve-Gasket/dp/B000C2APC4 I can't remember the last time I did one, but I don't think it's super complicated on the 4.0. For something like this, I'd torque down to spec. Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 22, 2023 Author Share Posted February 22, 2023 I see. Well I have no idea what the specifications are for the bolts. Like if I was to return the radiator from napa today I could very well possibly get everything I need plus the gasket without spending more money and just more or less using the money the rad costed me. And in a way this works out perfectly because those radiator hoses have to come off anyway for the conversion. So when those are out of the way it'll give more ease of access to everything I hope. I wish I knew what the spec was on the bolts. The only thing about this whole thing is cutting that heater control valve off and torqing the bolts down to spec. Last thing I need to do a strip a bolt or not tighten it enough since the back bolt will be kinda hard to get to Link to comment Share on other sites More sharing options...
acfortier Posted February 22, 2023 Share Posted February 22, 2023 This is going to be your friend: https://cdn.xjjeeps.com/pdf/en-us/1984-1993-factory-service-manual.pdf Says 55 in-lbs (NOT ft-lbs). If you don't want to spend the $$ on a torque wrench, snugging them down with a 1/4" ratchet will be more than enough. I think there's a particular order that they should be tightened, found in that FSM above. Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 22, 2023 Author Share Posted February 22, 2023 The mechanic is telling me it's just a different way of a conversion that I have now. The rad cap is at the highest point and shouldn't have anything to do with my radiator leaking except poor quality. Now I'm back at square one on what to do. My grandfather is also telling me no don't do it that the metal Mac tank is a pressure tank hence the radiator cap. Now I don't even know if that should be full because my grandfather is telling me it should be about half full or so Link to comment Share on other sites More sharing options...
jpnjake Posted February 22, 2023 Share Posted February 22, 2023 12 minutes ago, Classy Comanche said: The mechanic is telling me it's just a different way of a conversion that I have now. The rad cap is at the highest point and shouldn't have anything to do with my radiator leaking except poor quality. Now I'm back at square one on what to do. My grandfather is also telling me no don't do it that the metal Mac tank is a pressure tank hence the radiator cap. Now I don't even know if that should be full because my grandfather is telling me it should be about half full or so It should only be completely full if you have an overflow tank. If not when the system pressurizes it expands and if it were completely full it would overflow, that’s what the overflow\puke tank is for Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 22, 2023 Author Share Posted February 22, 2023 Alright. So my Mac tank is full. It has a catch tank. Now I'm rethinking this. These aluminum radiators are just poor quality? Link to comment Share on other sites More sharing options...
jpnjake Posted February 22, 2023 Share Posted February 22, 2023 Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 22, 2023 Author Share Posted February 22, 2023 Yeah I got a plastic tank attached to my aluminum Mac tank. It does push coolant into there and keeps the aluminum one full Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 22, 2023 Author Share Posted February 22, 2023 By the way. The rad cap on my mac tank is 16lbs of pressure. What's the factory pressure it needs to be if anyone knows by chance? I considered doing a 14. I ask this because my head gasket is leaking oil. Has been since I bought it. Even smells hot after driving it and walking by it. I almost wonder if exhaust fumes are getting in causing higher pressure Link to comment Share on other sites More sharing options...
Airborne Janitor Posted February 24, 2023 Share Posted February 24, 2023 Took me 6 years from the time I bought it to where I could actually drive it. I've been there, I had my truck untouched for almost a year. The big things holding me back were time and money. So I made the time and I made the money to where my goal was I need to get this thing mobile and this is how much I'm willing to spend. I won't even tell you how much I spent to get my $900 MJ going, and it's still not done, but I'm glad I kept at it. Having a truck I wanted as a teenager, and now being able to drive around with my daughter in it is priceless. Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 24, 2023 Author Share Posted February 24, 2023 Yeah I've definitely changed my perspective on selling it. That's for sure. Something I've had a question about is does the 4.0 have like a automatic choke on it? When mine idles it will run smooth and good but then it will idle back down kinda low then go back to normal and it does that if I'm sitting still. I'm trying to decide if it needs a head cover gasket. I have bought a felpro to have just in case. Its not running rough but I didn't know if when it idles down if that is something all 4.0's do or if that's a sign of something Link to comment Share on other sites More sharing options...
rokinn Posted February 24, 2023 Share Posted February 24, 2023 FYI....Head gasket is between the head and the block. Valve cover gasket is between the valve cover and the head. Saying you have a leaking head gasket is entirely different than having a leaking valve cover gasket. Link to comment Share on other sites More sharing options...
gogmorgo Posted February 24, 2023 Share Posted February 24, 2023 Valve cover gasket is an easy job. Head gasket is a little more involved. Only thing a valve cover gasket will solve however is oil dripping down the side of the engine. If you do it, don’t overtorque the bolts. Get them snug, tight enough they won’t shake loose, but no more or you’ll distort the cover and you’ll never get it to seal correctly after that. Spec on them is so light it’s not within range of a typical small torque wrench. Taking a vehicle off the road to fix it is one thing, but don’t leave it sit for too long. I did that with my first MJ. It sat for two years before I got started, and I got interrupted partway through and three years later I still haven’t got back to it. Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 24, 2023 Author Share Posted February 24, 2023 Gotcha. I'm doing my rad first then I'm deciding on doing the valve cover after that or do a whole upper engine rebuild/refresh Link to comment Share on other sites More sharing options...
Pete M Posted February 24, 2023 Share Posted February 24, 2023 wait, am I missing something? why is the metal tank full? either it should be roughly half full so the fluid can expand, or it shouldn't exist. that plastic tank is merely a catch for if the cap pops because that's the only way fluid will get to it. Link to comment Share on other sites More sharing options...
rokinn Posted February 25, 2023 Share Posted February 25, 2023 He says he is running it as an open system so that configuration would be correct. There's no reason not to go ahead and do the valve cover gasket first. Simple job. I've read that 3 core aluminum radiators are prone to leaking. I had a 3 core and it leaked pretty quickly. I went to a 2 core and have had no problems since (several years). It's all aluminum. Link to comment Share on other sites More sharing options...
Pete M Posted February 25, 2023 Share Posted February 25, 2023 anyone know what pressure the 87-90 radiators are rated for? Link to comment Share on other sites More sharing options...
gogmorgo Posted February 25, 2023 Share Posted February 25, 2023 It still shouldn’t be building enough pressure to pop the thing so long as that rad cap is working. Rockauto sells both 15 and 16psi caps as OEM replacements. The popular Volvo cap is rated at 22. But again, unless the overflow line is pinched or plugged, or the cap isn’t opening until way higher pressure than it should, it’s not making enough pressure to blow anything up. Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 25, 2023 Author Share Posted February 25, 2023 Now I'm very confused. How full should the metal tank be? Half or full to the ring? Everyone initially was saying full all the way because the thing is is my radiators keep failing. Not my tank. In theory if I have super high pressure wouldn't my aluminum tank would have blow up? It does spit coolant into the tank. That's for sure. My thing is where should I fill it to. Right now it is full. The catch tank is almost empty as of now Link to comment Share on other sites More sharing options...
Pete M Posted February 25, 2023 Share Posted February 25, 2023 does the tank have any hose coming up into the bottom of it? Link to comment Share on other sites More sharing options...
Classy Comanche Posted February 25, 2023 Author Share Posted February 25, 2023 @Pete Mit indeed does. I'll go snap some pictures, give me a few minutes Link to comment Share on other sites More sharing options...
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