I35GEEK

I received a P0128 error code. So I decided to replace the thermostat. I bought a new OEM thermostat and a metal gasket.

When I removed the old thermostat, there were pieces of cork gasket stuck on the engine block. I tried to scrape off the old gasket with a razor blade but it was really baked on. Also, you can not see entire opening. So I was doing it blind. What a PIA!

I went ahead and bolt on the new Thermostat and gasket even though there were pieces old gasket stuck on engine block. Bad idea. When I started the car, coolant was leaking from the gasket area. Now I have to repeat the replacement process.

Is there any advice on removing the old gasket? I cannot remove it with a razor blade and I cannot see. An interesting challenge!.The non-OEM thermostats come with cork gaskets but the OEM thermostats come with metal gaskets. The metal gasket would have come right off not in pieces. Sometimes, It pays to buy OEM.

I read mix opinions on using RTV. Should I use RTV with the new metal gasket? What color? Would that help stopping leakage if I still have the old gasket left on the engine block or do I have to remove the gasket regardless? What was supposed to be a 30 minute project have become a full day project. Ugh.

JSutter

iTrader: (46)

Clean it as best you can. Try using a mirror to inspect the area better. Two great options are:

Permatex The Right Stuff 90 or 1 minute if you need it fast.
Permatex Water Pump & Thermostat RTV if you can wait 24 hours for it to cure.

I35GEEK

Thanks @JSutter . The Inspection mirror is an excellent idea. I also heard about carbide tip scrapers which is supposed to work better than razor blade scrapers. I'll get both and see if I can scraped off that baked on old gasket. I have the new metal OEM Thermostat gasket but I thinking about using Blue Permatex gasket - I am not in a hurry. I want to do it right and not having to do this another time.

Which option should I go for and why?

Gasket Options:
1. Scrape off old baked on gasket. Inspect using mirror and try OEM metal gasket again (it leaked the first time because I did not clean it very well).
2. Use only blue Permatex after scraping the contact service clean. Do not use OEM metal thermostat gasket.
3. Use BOTH blue Permatex & OEM metal thermostat (is this over kill?)

JSutter

iTrader: (46)

Cleaning it is still top priority no matter what. Out of those, I like option 3. A thin coat of gasket maker on the engine side will hold the gasket in place as well as seal any issues from age/old gasket/etc.

I would not do gasket maker only because the mating surfaces do not have a grove like other parts of the engine that seal with only RTV.

Child_uv_KoRn

iTrader: (7)

fine SS wire brush

I35GEEK

Thanks. Another great tip about fine SS wire brush. When it comes to mechanical work, it is all about getting the right tools. So I am going to order a couple of brushes.

Reality sucks

iTrader: (3)

Do not use any sealer.

If you feel comfortable enough in doing so, Take the 3 Studs Out. If you can get them out, it makes clean up so much easier.
A razor blade, some brake cleaner and have at it. The oem gasket is best, put it on dry and roll on even if it is a aftermarket paper gasket.
Do not use any form of sealant.

I35GEEK

@Reality sucks. Interesting perspective. I was thinking the same way. I have done lower oil pan gaskets with and without sealant. Once you put RTV gasket on an engine, it will be forever stuck on it. So that is why I am asking for advice from others and their experience with thermostat gaskets. I know once I use RTV on the engine block, it will be stuck on it forever. It is already a pain to clean an lower oil pan gasket when the mating surface is in full view. It will be almost impossible to clean RTV on a thermostat engine block with such little space and limited view.

So I may take your advice and try it one more time with just the OEM gasket with no sealant after some serious clean up. The non OEM gasket that is baked on is likely paper. So I would assume with some liquid such as brake fluid. it will help to soften it and make it easier to remove.

What do you mean by removing the 3 studs? Which 3 studs?

User1

And don't scrape/scratch the gasket surface with anything more than plastic. And no abrasives.

Reality sucks

iTrader: (3)

@I35GEEK The paper gasket that is on there now is likely and aftermarket, Given the age of these cars, That thermostat and housing is likely an aftermarket thermostat. Nothing wrong with that. The Oem gasket is metal here for that reason. I've installed them both ways without issue. It just needs to be installed Dry. Be sure to cover the alternator also. Use some Plastic shopping bags so that nothing falls into it. A baked on gasket likely was put on with something other than rtv, Indian head shellac is great for holding difficult gaskets in place, but can be PITA to remove after some years of heat under a gasket.

At the thermostat housing, the studs that stick through it. They are Inverted torx e4 I believe. Attempt to back them out. If they don't budge, leave them alone, if one breaks however that's another job in it self. Clean around them as best at you can if you cant get them out. Some cars have them, Some don't. if yours does. try to remove them. The majority of time spent on these engines is in fact Clean Up. Scotch Bright Red pads work wonders and are alum safe.

I35GEEK

@ reality sucks. My housing does not have Inverted torx e4. So one less thing to worry about. I like your suggestion about the red Scott pads to clean up the surface. I will get some.

I have the new thermostat removed again. So far, brake cleaner and the carbide tip scraper seem to be working. The inspection mirror allows me to see the upper side of the mounting surface that is hidden. It is still a pain to clean that part.

We have another family car that I can drive. I am not in a hurry to finish this hellish project. I need to just do it right this time; not necessary fast.

I35GEEK

Just reporting back to all those who gave me feedback. I took everyone’s advice. The inspection mirror was key. It allowed me to see the hidden areas of the thermostat mounting surface.

I used lots of brake cleaner which helped to soften the stubborn paper gasket. I used a carbide tip scraper to remove the big pieces of baked on gasket and followed up with a one sided razor blade to remove the remainder smaller gasket pieces. Once complete, I did one final round of brake cleaner and the red/pink scotch brite sponge.

I did not use RTV gasket because I wanted to try the OEM metal gasket again. RTV will be stuck on the engine mount forever.

The other key is to carefully torque the 3 thermostat bolts to factory specs ~75 to 99 inch pounds. With some finessing and the right adaptor/extenders, I was able to squeeze my torque wrench in there to do it properly.

I started the car, burped the coolant and voila - no leaks. What a relief! It can’t imagine having to do this a 3rd time.

Like they say - do it right the 1st time. Take your time. Mechanics are like surgeons. Don’t rush them :-).

ChrisMan287

iTrader: (34)

I was going to suggest just copper spray on the metal gasket after cleaning the mating surface really well but nice to see you have it all sorted out.

Reality sucks

iTrader: (3)

Glad you got this resolved. The carbon scraper was the trick. Sometimes it can Feel Like Surgery, I do this everyday.

User1

Good job. Despite using abrasives Lol

I35GEEK

I neglected to mention that I started with a plastic non abrasive scraper. It did nothing to remove the baked on paper gasket. So I had to be brave and start using other more aggressive but mild tools. My back up plan is to use RTV silicone if I ended up scratching the aluminum mating surface to the point where it would leak with a regular gasket. Thankful I did not have to execute that plan.