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Discussion Starter #1
Hi all, I've had my 91 N/A MR for a little over 3 months now, after I got the car I did the basics for service, changed oil, changed oil filter, checked transmission fluid along with flushing the radiator and cooling pipes in an attempt to seize a slight overheating issue, well since then, the issue has remained, the car will run right at 180C after its warmed up ( *which takes about 10 mins to do so* without the thermostat, since the car has not had a thermostat since I've had it ) doesnt matter where I am, in traffic, or on the highway. The fact of the matter occurs when I turn on the AC, then the car starts to overheat and will continue to get hotter unless I turn the AC off, anyways thats kinda like a side story.

As a second attempt at fixing that possibly and also doing some maintainence on the car I'm pulling the cylinder head and having it resurfaced, also going to reseat the valves and such, since I have half the engine out kinda, I'm up to suggestions as what other things I could try doing to the engine to get some more power/and or help with the heating issue.

I was thinking on getting cams, although me being in Panama City, Panama makes it kinda hard to get stuff to and from the US in a timely and cost effective manner. So I was wondering, I have a spare motor, with spare cams, is there a method that can be done to resurface/ grind my other stock cams to specs that I could provide to a shop that does this? or is it something way beyond that point of complication..lol..some help here.

Aside from that, again I'm open to any suggestions on what to take a look at while the cylinder head is pulled.

Thanks! ;)
 

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you could try to get some used 3sgte intake valves and swap out yours for them. They are 1mm oversized and just require recutting the stock valve seats. thast shouldnt cost much more since you are already getting a reseat. then i would port the head, exhaust side is terrible! as for cam grinding, i am sure you can find a shop that has the capability of doing this. it is usually a more expensive modification and requires some sort of engine tuning because the stock ecu will not be able to handle the differences.
also, why not get a new thermostat??
good luck!

edit: oops forgot to mention the standard mods of intake, header, and exhaust, which i am sure you can find a skilled welder to make for you.
 

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Discussion Starter #3
Well, thanks for the reply, specially in regards to the Cams thing, I actually thought that no further modding needed to be done to notice a diff in power level throughout after just grinding the cams.

..as far as the oversize valves, well 3SGTEs are very scarce around here, all of em are inside cars running amok :p ......... I've got my eye set on a fully built 3SGTE clip for sale here in Panama but need to gather that money before I set off on that, so its not in the ballpark right now.

The porting of the head, any shop can do this? the one who can shave it for me also could do this? if thats so what would be the price range on this (we deal with US money so a rough estimate is good) ?

As far as the thermostat goes, I'm weary of putting it on because of the slight overheating issue which I"m trying to resolve, basically I'm pulling the head, doing everything to stock specs, then checking out the heating issue if it continues the next thing to take a look at would be the radiator core and cooling system in detail.
I figure adding a thermostat to the equation would make it worse for the heating issue.

IF the heating issue is resolved then I'll go with these changes that I wanna make for it. Given the time down and money are not excrutiating factors.

ppphheeww another long post.. LOL..... Thanks for the input and please keep it coming!
 

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No you dont need further tuning with cams, but the reliabilities sake its a good idea to get at least an SAFC
 

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If you want that "fully built" 3s-gte then why are you wasting your money on an engine that you aren't going to keep?

Anyways, I would say just go with cams if you want to get a little more power out of it. It's the best bang-for-buck with the situation that you are in esspecially if you were looking for something to wake up the engine a little. I wouldn't waste my time on valves in your case.
 

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Discussion Starter #8
ok, but like you mentioned before,umm I just want some more UUMMPPPHH to it during this time that I'll have it before I go turbo, would the SAFC be a wise investment at this point or not?..

Thanks for the info, really helps..
 
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About your heating problem, MR2s have a set way to refill the cooling system. If you look under the front hood, pull out the spare you will see some clear hose rolled up and tye wrap and connected to a valve right at your heater control valve. There should be two pieces of tubing about 3/8" X 2.5 feet long. You then have to remove the plastic cover around the hood latch because the radiator vent is at the top of the radiator, it looks like a radiator drain valve. The one on the heater line uses a screwdriver to open and close it. The problem with MR2 is that the front of the car is so low that when you filled the system it traps air in the front of the car. The only way to get all the air out is to run these hoses up as high as you can and support them and then open both valves and turn your heater temp to full hot and then fill the system as you normally would. When you get it full you will see that both of the hoses will have fluid in them up about a foot and a half, equal to the level of the fill neck at the back of the car. Of cours the car needs to be on level ground.

That will get your system completly full, now as for not having a thermostat that WILL make you car overheat. HOW? By not letting the fuild stay in the radiator long enough to be cooled before it returns to the engine. Having the stat out lets the fluid pass thru to quickly no heat is lost and it comes back almost as hot as when it left the engine only to be heated up even more. And then when you throw the load of the heated air from the AC condensor, the system just can't take it.

hope this help, sorry for the long read
later WD
 

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Discussion Starter #10
Ok, thanks for the input, as far as refilling the system, I did that following the manual and reading what you just wrote it seems thats exactly what I did with some steps that dont apply, reason being that the Heating on this car was eliminated by the prev owner, *his mecanic did that...go figure* actually they replaced the engine on the car and when that was done they just didnt plug the heater back in, and just plugged the ends on the parts of the cooling to hold the water in. Anyways, it seemed I was able to get that to fill up ok and make sure no air was in it.

As for the thermostat, I'll go ahead and get a new one. Also I'm thinking on the radiator cap too, what PSI should the radiator cap be?.......

Aside from that, any suggestions as far as the headwork?.

If I wanted to regrind the camshafts, can that be done just in a matter of like resurficing it like you would the cylinder head, kinda like to get it back in spec without going to the extreme changes..? or is this something thats either not benificial or too difficult?

Thanks for the input, this is really helping me out here :D
 
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Your cams shouldn't need to be "resurfacing" unless you have had a oiling problem. I have run engines for over 250K miles and the valve lash was still in specs. But if you are wanting to change the specs on the cams from stock then they will have to be reground and they may have to be welded up before they can grind them to what you want. It all depends on what you want the specs to be, what mods you are going to do to the rest of the engine package. Reground cams without mods to the intake and the exhaust will IMO just be a waste of cash. As far as the rad cap goes just stick with the stock psi, it should be marked on the cap.

later wd
 

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Discussion Starter #13
ok that makes sense, I'll play it safe for now, I'm thinking on putting headers but it wont be right this moment, I'll stay with the cams how they are for now.

thanks for the info.
 

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Is your radiator somewhat clogged so some of the fins aren't cooling the water the way they're intended? Does your water temperature drop quickly when you turn your car's heater on at full blast?
 

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Discussion Starter #16
Well the heating system has been eliminated and disconnected from the rest of the heating assembly by the prev owner when they changed engines. As for the radiator, the prev owner supposedly flushed it, although I'll take a look at doing that myself also, I'm also interested in comparing how the temperature would behave if I take out the AC core and leave just the radiator core head on into the wind just for testing it out.

Thanks for the help.
As for dropping it...... :D
 
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