Reconsidering engine rebuild! Need wiseman advice!

[DSMOCTANE]

-So heres the deal, I was planning on doing a complete stock overhaul on my 99' GS because at the time I had thought my rings were shot. Long story short, my father and I ended up pulling the head to discover a burnt exhaust valve in cylinder #2 as well as a cooked head gasket. At this rate I may just stick to rebuilding the head, considering that cylinders 1,3, & 4 had all read 180 psi during the compression check before all this. It was just the damaged cylinder #2 that had read less than half of the others! Since shes just my n\t daily driver, I think I may just stick to rebuilding the head for now. 180 psi sounds not too bad you'd say for those other cylinders, right? There was no significant ridge around the edges of each cylinder including #2 as well, and not any signs of black carbon built up on the plugs and rest of the head (hinting limited piston ring failure.) I have three questions for you guys: 1. I have a great machinist who will inspect, test, clean and resurface the head for me, but what do you think as far as just replacing that cooked valve and leaving the rest of the valves remaining? 2. Also, is it possible to micro-polish our cams if there is limited wear? 3. Lastly, after rebuilding the head is it alright to run fully synthetic oil if I ran just plain high mileage oil before? (Any recommendations appreciated)

 

[Anubis_4_99]

-So heres the deal, I was planning on doing a complete stock overhaul on my 99' GS because at the time I had thought my rings were shot. Long story short, my father and I ended up pulling the head to discover a burnt exhaust valve in cylinder #2 as well as a cooked head gasket. At this rate I may just stick to rebuilding the head, considering that cylinders 1,3, & 4 had all read 180 psi during the compression check before all this. It was just the damaged cylinder #2 that had read less than half of the others! Since shes just my n\t daily driver, I think I may just stick to rebuilding the head for now. 180 psi sounds not too bad you'd say for those other cylinders, right? There was no significant ridge around the edges of each cylinder including #2 as well, and not any signs of black carbon built up on the plugs and rest of the head (hinting limited piston ring failure.) I have three questions for you guys: 1. I have a great machinist who will inspect, test, clean and resurface the head for me, but what do you think as far as just replacing that cooked valve and leaving the rest of the valves remaining? 2. Also, is it possible to micro-polish our cams if there is limited wear? 3. Lastly, after rebuilding the head is it alright to run fully synthetic oil if I ran just plain high mileage oil before? (Any recommendations appreciated)

My 420A's compression reads 220PSI, yours seems a little tired, but if it is just a daily beater and you have no immediate plans for any power out of it, i would just rebuild the head and go. Your above the service limit for our cars compression wise, just a little on the low side.

As far as just replacing the valves, if you have it out, why not just do them all and avoid any further problems? I doubt it's prohibitively much more expensive, and the little bit of extra cash is cheap insurance to not have to do it again.

Thats all just my .02 though, so take from it what you want

 

[95talongirl]

^^

That's correct. You are on the low "service" end for the compression on the 420A. It's still acceptable, but it should be more like 200-220. I also agree with the above statement, if this is just your daily driver, then you should be fine with just replacing what's wrong with it and go.

 

[Josh97eclipse]

At 185xxx before I pulled my motor to put in my built motor my compression was at 215 all across. Id say your is on the lower side but it could also run for another yr or more. All up to you. If you have planned to do a rebuild why do it as a "stock" rebuild? I would upgrade the internals.

 

[SoCalK61000]

if your planing on keeping the car id say just throw some rings and bearings in and do the valve and a fresh valve job, what better to know that your engine is 100% and running like it should an ebay re ring kit is only a couple hundred bucks

As far as the oil goes if your just gonna do the head then synthetic oil will be fine to run, if you decide to do the bottom end then you will have to break it in then switch over to synthetic

 

[Colt4G63 also]

I would say just do the head, and as for the valves, your machinist will probably tell you to just replace the valves that are bent or damaged.

I'm not sure about polishing the cam, since there's no bearings, I'm pretty sure that you would normally leave that alone.

 

[Bannery]

Hello Everyone!
Do not be angry at me because I break the English language,
My car: Mitsubishi Eclipse 99 /420a/
Next my problem with him:
If I wind it the servo government , lifts the idle speed, 1200k
You are standing in a situation if I am rolling do it,
What may be the problem?
Please let somebody help because I am puzzled in this,
Greet nicely everything,

 

[Colt4G63 also]

Hello Everyone!
Do not be angry at me because I break the English language,
My car: Mitsubishi Eclipse 99 /420a/
Next my problem with him:
If I wind it the servo government , lifts the idle speed, 1200k
You are standing in a situation if I am rolling do it,
What may be the problem?
Please let somebody help because I am puzzled in this,
Greet nicely everything,

That's total gibberish. You're going to have to try to do better.

 

[XiKeiyaZI]

That's total gibberish. You're going to have to try to do better.

I'm surprised you could even pull any information from that.

My head hurts...

A+ for trying, though. English is an illustrious language.

 

[Bannery]

I apologise for my bad English usage,

My problem:

when the car is idle and when you turn the steering wheel, the idle rpm increase. 1200K
What may be the problem?

 

[Colt4G63 also]

There is a steering pressure switch that sends a ground signal to the ECU when steering fluid pressure increases. The signal is used to increase RPM when the power steering pump is doing work, so that you get good steering pressure and don't stall the engine.

Ps. Don't European DSM's have a N/A 4G63?

 

[Bannery]

There is a steering pressure switch that sends a ground signal to the ECU when steering fluid pressure increases. The signal is used to increase RPM when the power steering pump is doing work, so that you get good steering pressure and don't stall the engine.

Ps. Don't European DSM's have a N/A 4G63?

Thank you for your answer,
Not, this 1999 420a engine,
This then normal the 420a engine?

 

[Colt4G63 also]

Thank you for your answer,
Not, this 1999 420a engine,
This then normal the 420a engine?

Nevermind. I just researched a little, and apparently they did get some 420A engines in Europe after 98.
http://www.dsmtuners.com/forums/newbie-forum/369368-na-4g63-air-fuel-control.html

 

[DSMOCTANE]

Thank you all for the great advice! I actually just ended up getting an entire new motor and transmission for a very solid price! The head and block of the new motor are in much better shape anyway, but yet I am still going to continue with the re-ringing, valve seating, and resurfacing of the head and crank! I plan to slowly invest in boring and stroking the other block and getting it ready to become a boosted 420a! I want to have an Eclipse that proves worthy to the 4G63's, as well being something custom and totally unique! Thanks again guys!