Thread: Bad Thermostat cause a misfire on Cylinder #5?

Fix your coolant leak first.

The likelyhood of you popping a head gasket is so small, they rarely go on these motors. So many people mis-diagnose a coolant eating problem or leak problem, the real main cause is the intake gaskets and coolant elbows.

I would do a full tune up with everything, then see where you are at. That means intake gaskets, coolant elbows, spark plugs and wires and so on. If the intake gaskets are still the factory ones, you are on borrowed time anyway.

Thanks for the advice.

I have replaced the water pump and LIM gasket about 3.5 years ago when i noticed coolant resting by the injectors. When I did the LIM I used the aluminium gasket. When I did the LIM I replaced the elbows with the plastic ones and had to go back and replace them with the aluminium ones about 1 year ago along with the wires...

So just to confirm your advice I should go ahead and replace the thermostat (been wanting to upgrade it to the 180 degree one anyways), spark plugs and wires? Then see if the temp subsides?

Thanks again!

For 10 bucks, it never hurts to replace the thermostat but a 180 won't change anything though. The temps will still climb above 190-195 because the fans are still at stock settings when sitting in traffic, on the open road it will run 10º cooler but it's not like that 10º even matters.

If you say you are still leaking coolant somewhere though, I'd still try and figure that out aswell.

Then look into the misfire issue, pull the plug and inspect it and replace them if you think it's needed or if they havent been done in a very long time.

Originally Posted by koRnhead

Why do you need a torque wrench for spark plugs?? Just snug them when you put the new ones in......

Agreed. Just tighten them by hand and when you feel resistance, just give it like half to a full turn or something. You'll know when it's good.

I am used to my car EVEN at idling staying at well below 160 and never going higher than 160 EVER... Much less my coolant temps have NEVER really fluctuated... I rather take care of the problem now when I am able before it develops into something major later... Just my thinking behind it... Let alone there the coolant reservoir always seems to be missing coolant, even though I don't see any leaks..

Like my girl said at first, "don't get on it, it won't get hot" fixed it from getting hot except for idling... Now she says, "Just don't sit too long in one spot and it won't get hot" I just don't agree with that train of thought.... WHAT happens when I'm stuck on the highway in bumper to bumper traffic and I can't go anywhere and that's the day the water pump decides to fail completely! Which is TOTALLY my luck... I'm screwed. Rather just get it right now, than press my luck and hope for the best... No offense.

As far as the spark plugs, it's just what I've heard and read... You don't have to do it if you don't want. Just makes me feel better & what's the harm in that? I've also wanted a torque wrench because it makes me feel more secure about the work I'm doing... And at the risk of opening another can of worms I also like to torque down my lug nuts to make sure I don't do any damage to the hubs... Which I have actually done by over tightening my lugs and damaging my hubs before... Used a impact...

Another fact is it makes tightening very easy now when I do my lugs and I don't have to worry about over or under tightening them.. much more breaking my back... To each there own I guess and I hope this doesn't affect the input I'll receive because I like using a torque wrench

BUT for those that are interested here is some good info from NGK on why torquing them is important. FYI They say to torque 20ft/lb for new plugs, 11ft/lb for reinstallation of used plugs. FOR anyone that cares....

"""1. Installing spark plugs

Torque is one of the most critical aspects of spark plug installation. Torque directly affects the spark plugs' ability to transfer heat out of the combustion chamber. A spark plug that is under-torqued will not be fully seated on the cylinder head, hence heat transfer will be slowed. This will tend to elevate combustion chamber temperatures to unsafe levels, and pre-ignition and detonation will usually follow. Serious engine damage is not far behind.

An over-torqued spark plug can suffer from severe stress to the Metal Shell which in turn can distort the spark plug's inner gas seals or even cause a hairline fracture to the spark plug's insulator...in either case, heat transfer can again be slowed and the above mentioned conditions can occur.

The spark plug holes must always be cleaned prior to installation, otherwise you may be torquing against dirt or debris and the spark plug may actually end up under-torqued, even though your torque wrench says otherwise. Of course, you should only install spark plugs in a cool engine, because metal expands when its hot and installation may prove difficult. Proper torque specs for both aluminum and cast iron cylinder heads are listed below.""

Rather be safe then sorry...

Back to my problem at hand... When inspecting the aluminum elbows I kept getting hit with coolant that seemed to be coming from the belts... I did some investigating & googling and found that usually when setting at idle and experiencing higher temps that 9 times out of 10 it has to be the water pump... The amount of coolant that was hitting me was minimal but still I would think it would give off the symptoms I've been having...

Knowing that I did my water pump 3.5 years ago, does it seem like a long shot that the water pump could be bad again from the thermostat failing?

That o-ring around the thermostat was CRAZY bad like pieces of the o-ring were nonexistent... Let alone there not being any gasket or gasket material attaching the housing...

Also read somewhere that a bad thermostat not taken care fast enough can cause the water pump to leak because of the higher than usual temps.... Like I said before I might be doing work that seems meaningless BUT for me not seeing that temp gauge fluctuating lets me sleep easier and have less worries when my girl or even me is taking my car more than 30 minutes down the road and on a highway... AND for $45 a Water pump and a rubber gasket seems well worth the shot... In my opinion.

Again hope I didn't offend too many people and still hope for any and ALL the advice you can give me... Even if it's giving me a hard time about using a torque wrench on my plugs

THANKS!

grab the w/p pulley with two hands, engine off or course, then push and pull the pulley, if it rocks back and fourth the pump is bad. water pump will sling a stripe on the hood from the coolant off the belts too most of the time.

I have NEVER used a torque wrench to install spark plugs and NEVER had an issue due to that. NGK only puts that on their website to avoid lawsuits from morons who don't know how to put in spark plugs properly. It's call CYA (Cover Your Ass)

First of all let me apologize I misspoke (mistyped ?) when I was saying 160 I was confused and meant the mark between 160 and 210 (What would you say that is? 180?)... I slapped myself on the head the day after I posted this and when I went out to my car to do the water pump...

So the temp before the water pump and thermostat was over close to 210 and a lot of the time going over... After the new zzp 180 thermostat, it was over "180" climbing close to 210... NOW after the I have done the water pump replacing the paper gasket on the water pump with the Felpro rubber gasket, a new water pump and new radiator cap the temp has subsided. The temp now rest at right below the "180" mark and sometimes sitting in traffic it might hit that "180" mark or go 1 or 2 notches above... Almost perfect from where I am used to it being...

The first day I put the water pump in the temp was kind of doing the same thing with getting to 210 but after the last day and a half of me bleeding it every time I got done driving it and monitoring the coolant reservoir (which don't seem to be dropping now) the temp has subsided and seems to be getting better everyday...

For those interested I used my torque wrench on the water pump with using the spec I found in another forum of 10 ft/lbs on the small bolts and 13 ft/lbs on the big ones... I didn't use any gasket material or anything for that matter on the rubber gasket..

NO leaks, from what I can see (knock on wood). Well besides whats seems to be a couple drops every other second around the area you jack the car up at the front of the car behind the front tire on the passenger side... Should I investigate more? I figured it was water or something from the A/C?? Because this isn't where the puddles have been coming from...

Also wanted to mention that I ran into an extra pulley I had to remove that I wasn't expecting from watching the Youtube videos on replacing the water pump on our cars. I suspect because I have a GTP there was this extra pulley... I am mentioning this because I ALMOST couldn't find the correct Align wrench to take it off half way through disassemble...

I still haven't replaced the spark plugs because it was getting too hot in the Florida sun, my back was too sore, and I cut up my hands pretty good (let alone there're swelling) doing the water pump this weekend... I DO have to say A LOT of the hesitation to WOT is gone now but a TINY, really, almost unnoticeable hesitation is still there. ALSO the day after I did the water pump the check engine light went off for the misfire on Cylinder #5 for some reason?? Not that I complaining BUT still going to do the plugs just not so sure on replacing the wires yet... IDK



SO pretty much last of my questions... My guess on the temp dropping is because more and more of the trapped air is working its way out?? How many days do you think it will take to settle? AND should I keep trying to bleed the air out? Or is the air pockets going to work themselves out?? I KNOW being anal now Also, still puzzled about the check engine light going out... Hoping after I change the plugs that little bit of hesitation (only someone that has drove the GP GTP this long would notice it) will go away... I know I'm being anal about the temp and hesitation... Sorry

Also some thoughts on that small leak behind the front passenger side tire?

Thanks to you ALL for your guidance, you have gave me that little bit of confidence and hope to follow this through! First water pump replacement BTW! YAY!

THANKS GUYS!

First big line after 160 is really 190º if you read the temps with a scanner/OBD2 reader, the temps will ALWAYS move around when moving and during stop and go traffic. Thermostats open and close and what not so temps will move a little bit.

Touch the so called "leak" with your hands, water will be water and coolant is coolant. If you are running the AC all the time, then it's likely just water because it must vent the condensation somewhere.

Last update.
FINALLY did plugs and wires. I didn't do much research on plugs like guess I should of and ended up getting the Autolite AP606's... I guess if I ever want to upgrade to a smaller pulley I need to do the 104's?

But even still she's purring and gets on it nice and good again (KNOCK on WOOD she stays that way)! LOVE that feeling being pushed back into the seat smashing that pedal Let alone MPG went form 16.9 to 22 after resetting it.


Thanks again to everyone!

Was also thinking about hitting up the junkyard and getting a Northstar throttle body... I also see a TON of them on ebay... Could any or somebody tell what ALL I would need to get??

From what I've read I need a throttle body off a 2000+ Deville? Is there anything else I would need? Thinking a gasket kit and from what else I've read I would need the TPS and that throttle cable bracket from zzp (not really wanting to rig anything)? How about the maf sensor? Do I use the GP GTP's or the Northstar's? I also imagine I would need gaskets?

Should I just open a new thread since this problem has been solved?

Thanks again EVERYONE!!

I thknk this thread has answered some of my questions

http://www.grandprixforums.net/threa...+ADAPTER+PLATE

not sure what is what right now... doing research... not as cheap I thought it was going to be Parts are adding up quick!