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Valve cover gasket replacement gone wrong


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2013 Mazda 3 I touring 152K miles

I'm changing the valve cover gasket on a newly purchased used car. The pre inspection called for a valve cover gasket replacement. Things are going poorly even though everything I read says it is easy to do yourself.

The problem I'm having is things are going wrong and I'm guessing now at what to do and made things worse. So I'm asking for help.

1. The gasket I ordered came and now that I have the valve cover off I can see the gasket is the wrong one. I ordered a new one but will take 3-7 days to arrive. What do I do to protect my engine?

2. The gasket didn't come off in the cover and is stuck on the engine but there is so much grime, oil and dirt, build up I'm afraid to pull it off in case the grime gets in the engine. I'm trying to clean around the gasket before I remove it but not sure what the best approach is. I'm afraid of getting grime and solvent in the engine. Can I clean it with motor oil? What is the best way to clean it?

3. Why is the gasket stuck on the engine? Every replacement I've seen it comes off with the cover.

4. I ripped out the variable valve timing solenoid because it was stuck on the cover with grime. Is it okay to buy the $40 one instead of the $200 one?

5. I can't figure out where the leak was. There is oil all over valve cover and caked with dirt, fur, and tiny feathers. The gasket looks fine. Could it be, I'm not solving the oil problem by changing the gasket?


I really want to work on my cars myself if I can but having issues with an easy level task is discouraging. I'll keep plugging through this issue but it shakes my confidence at the moment.

Well somehow I broke off the middle bolt and am in a quandary on what to do now. I'm guessing I need to take the whole valve cover off again, drill out the bolt, replace the gasket again, get a new bolt, and put it all back together. I'm not seeing how this is considered a DIY job now. I can't imagine what I did was the total cause of it breaking. But it is broken no matter what the cause.

Sorry to hear you're having trouble. This morning I asked the following question: Does anyone know any good tricks to remove a broken off valve cover bolt, preferably without removing the valve cover. It broke while tightening after replacing the gasket?

Scotty Kilmer's answer was: Well if you have room you drill out the old one and then retap it with a tap and die but that's not that easy working with the valve cover on.

I hope that is some help.

Please put your answer in the "Your Answer" box at the bottom of the page. Thanks.

8 Answers

Cover the valve train with clean rags or something to keep as much dirty stuff out of the engine as possible. Use a shop vac to remove as much of the loose stuff as possible before and during the old gasket removal. You may need a putty knife or something to scrape especially if gasket sealer was used on the old gasket. Compressed air can also be helpful to blow the junk away form rather than into the engine. After ALL of the old pieces have been removed clean the surfaces with some parts cleaner, Then go over the area again with the shop vac. You should be OK if you are careful and take your time. 

Personally, I would bite the bullet and buy the more expensive variable valve timing solenoid. My guess is that's the OEM part and it has a better chance of working the best for the longest. Good luck.

I didn't look it up, however I believe that may be an aluminum head. I've had good luck using the Permatex plastic scraper, and it won't scratch the surface. CRC gasket remover is also a decent solvent for softening gaskets.

I agree.

I thought about the shop vac idea, but I wasn't sure if it's a good idea to suck motor oil into one in case it could catch on fire, lol.


1. Cover the valvetrain with something like a towel to keep dirt and dust out, or just lay the cover back over it when you're not messing with it. 


2. Put rags or plastic down to keep particulates out of the valvetrain. Spray degreaser onto a rag and wipe in directions away from the valvetrain. You might be able to more liberally apply degreaser with a towel blocking the valves, but I would still be cautious. If it's really grimy, use a toothbrush to scrub the dirt and grime away while wiping the area often. 


3. The rubber gasket may be heat welded to the top of the engine. It's been there for 153,000 miles and 8 years worth of hot and cold cycles, or it was attached at the factory with an adhesive. Put the cover back on and very gently tap the sides with a rubber mallet. The wiggling cover should break it loose. Or use one of those plastic trim removers that are like mini crowbars to pry it up without risking damage to the top of the engine. Don't use anything metal, as steel will gouge the metal if it's an aluminum head. 


4. Don't buy any sensor that is not the OEM  part. You will likely have issues with the cheap sensor. 

5. Is the oil all around the valve cover gasket or concentrated in one area? You could have run leak dye through the engine to zero in on the source if it's leaking. The cover may not have been leaking and the build-up was from years of people spilling oil everywhere. 





This post was modified 1 week ago by Justin Shepherd

Good suggestions. I do wonder if oil just spilled. I checked and the oil looked a little over full but I'm looking at two dots on a rod. Maybe it was leaking and they topped it off to try to sell it.

The person who was selling it really seemed clueless about cars though. I don't think they've ever looked under the hood. So it may be just a bad oil change.

For example why I think she is naive about cars. The TPMS light was on and she said, "I was told Mazdas are always like that." I found the tires were all under inflated. I just filled up the tires and it was fine.

I stopped letting my girlfriend take her Mustang to the dealer to get oil changes done, because every time I'd look under her hood, there was oil mess all over the top of the beauty cover. People are more and more sloppy about their work cuz they don't care. It's not their car. I do all of our work, now. Haha. Good luck!


1. You can take a trash bag and cut it so that it fully covers the exposed head.  I've also used saran cling wrap to keep dust out of exposed parts.

2.  I don't think motor oil will work from what you are describing.  Just be careful, and slowly pull the gasket off.  You can purchase a Permatex plastic scraper and use it to lift the edges of the gasket easier.  Lift and pull the gasket away from the exposed head as much as possible.  If some 'crumbs' fall onto the exposed head, just remove them.  Don't be in a hurry.

3. It depends on the gasket material used by the manufacturer, plus age and heat.

4. Don't just look for the cheapest replacement, look for a good warranty as well.

5. Fur and tiny feathers?? I don't have an answer for that one.  Unfortunately yes, if you misdiagnosed the leak you will need to figure out where the leak was actually coming from.  You can purchase a dye detector kit for engine oil, and follow the instructions.  

I suggested motor oil because that is how you clean the surface of old iron sewing machines and thought it might work here too but I guess engine heat is the biggest difference.

I'll test the next time I do this to trust but verify the diagnosis.


What do I do to protect my engine?

I would just put the valve cover back over it.

I'm afraid of getting grime and solvent in the engine ... What is the best way to clean it?

Brake cleaner should work. Almost any solvent. Gasoline is good at dissolving crud too.

Use as much solvent as it takes to clean it and don't worry. When you're done, then run the engine a little to warm it up a bit, and then you should change the oil.

3. Why is the gasket stuck on the engine? Every replacement I've seen it comes off with the cover.

it's common to stick gaskets down in a few spots with grease or RTV so it doesn't move around when you're putting things back together. Then over time the heat bakes it on.


4. I ripped out the variable valve timing solenoid because it was stuck on the cover with grime. Is it okay to buy the $40 one instead of the $200 one?

Not if you don't to be doing the job again soon. Buy once, cry once.


Could it be, I'm not solving the oil problem by changing the gasket?

Could be. You'll find out when you're done. If it's not then at least it'll be easier to track down with a niece clean valve cover.


There is oil all over valve cover and caked with dirt, fur, and tiny feathers.

Critters were making homes under the hood.


it shakes my confidence at the moment.

I find with cars, things rarely go without a hitch. Things are often not what they seem at first glance. But that's life. You just have to roll with the punches. When you finish you will get a feeling of satisfaction, and the next time you will have more confidence. It's part of the learning process.

Thanks man. It helps. I'm heading over now to finished cleaning it up using everyone's advice. I'm feeling confident now.


1. Put some improvised cover like some sort of a clean rag or a stretchable wrapping film or else over the engine / whole motor compartment - that is what Ive done many times. No use being overly concerned about cleanness here: dust contained in normal air is not a threat.

2. Normally one should first clean and degrease all the surroundings, and only start  removing the valve cover afterwards. But your situation is not a drama either: now that your cover is already off, you might (and this is what Ive done it in a similar situation) want to just get a powerful industrial vacuum cleaner, which is not afraid of any kind of dirt and liquids, and vacuum-clean the area. If any sticky dirt remains, take pieces of clean fabric, and maybe an old toothbrush as well, and carefully wipe the sticky dirt off, with or without solvent, directing all your wipe movements away from the open engine internals. It requires some patience, but it is not a difficult job, and nothing to be afraid of doing. Afterwards, clean all the residual particles off using the vacuum cleaner. If you are careful like me, your engine will be saved 😉 I also use small amounts of alcohol to do the final clean pass on the surfaces which come in contact with the gasket.

3. Are you sure that grime and dirt are the only things holding the gasket on the engine head? Sometimes, when engine parts get warped due to engine overheating, previous owners try stopping leaks (which are no more stoppable by plain gasket replacement) by glueing the gaskets to engine heads using everything they have at hand as glue. Unfortunately, this band aid too often does work short-term - just enough for the previous owner to get rid of the car.

However a glued gasket is not necessarily a sign of severe engine damage due to engine overheating: sometimes owners / bad mechanics try reusing an old gasket after doing some work under the head cover just cause they do not have a suitable new replacement gasket at hand; then they understand that the old reinstalled gasket leaks, and try reinstalling it once again - this time with excessive amounts of some glue or sealant... 

I am not trying to scare you: just recommending, that if you find out that your gasket is glued to the engine head, you (after you cleaned the glue off) might want to check the flatness of the respective engine head and valve cover surfaces to make sure those are not warped. Warped surfaces can still be repaired, but it is a huge expensive job for a workshop which has certain machinery. 

4. No idea.

5. Probably you cannot figure out the exact leak location cause the leak was happening not in a certain spot, but along a long line - maybe even all around the gasket. Hence, the gasket probably looks fine cause it is mechanically undamaged: it does not have any specific weak spots which would leak, but is just unable to do its job - either cause the engine surfaces which come in contact with the gasket are warped, or, in the best-case scenario, cause the gasket may be so old and therefore so hard, that it simply does not have the elasticity to seal anything any more. I sincerely hope that in your situation the latter is the case.

"having issues with an easy level task is discouraging"
Based on my long-year experience, when working on my cars, I always pre-assume that every task will be harder and take longer than expected, will have hiccups not described even in the dealer documentation, and may reveal problems previously unnoticed. C est la vie - I am already used to it. But having coped with it in the end brings a pleasant feeling of accomplishment 🙂 


Thanks for the suggestions. I did budget in for mistakes but this seems just so weird. I ordered the gasket for my car and took off the valve cover and the gasket is wrong. I searched and only one site had the correct gasket when I put in my car. So I ordered it from there. The car industry and all of the ones that live off of it are just huge.

I even went to Auto Zone and O'Reilly's to see if they might have one in stock. The guy at AutoZone argued with me about the gasket, even though I showed him a picture of in the engine. The guys at O'Reilly's seemed to know it was a Ford engine. I guess I should've had them look up a gasket for that. They might have it in stock.

I'm still trying to wrap my head around the huge car universe.

I guess ignorance is bliss but learning all this stuff is fun.

"but learning all this stuff is fun"
Well, actually it is fun, and full of discoveries. How about my recent discovery: that regardless which aftermarket Benz valve cover gasket you order - the cheap Elring or the more pricey Hein Reinz - both are a) noticeably thinner than the OEM gasket, and, b) if you order a kit of two cheaper Elring gaskets for your V8 (which has 2 gaskets), a kit may arrive with an Elring order number on it, and with one Elring and one Reinz gasket inside (Elring and Reinz being words imprinted in the gasket material and obviously too hard to get rid of)?!
While ordering a 5 times more expensive OEM gasket is not an option, but not cause of the price, but cause manufacturing of those stopped years ago, and if you order one, you either (depending on how honest your supplier is) get smth original, but aged and weathered and cracked enough to prohibit installation, OR the mixed kit described above - just at a higher price?
So - yes, repairing your own car is great fun. If you start to, life will no more appear boring 😉


As others have said, take your time and do it right. You will feel much better in the end knowing it is nice and cleaned out, with a gasket that is doing it's job. Also don't count yourself short, I wouldn't call changing a valve cover gasket something a beginner does, I would call that an oil or differential fluid change.

For that job, slow and steady wins the race, or you get to do it over again.

Topic starter

I can see the gasket is tacked down at a couple of places. And that is what the instructions I have say to do although it looks like there is way too much compared to my instructions. I'm guessing this was a factory install of the gasket because it looks like a machine did it. But I'm just guessing. The gasket looks to be pliable. I pulled on it where the sealer is and it came off the sealer easily. 


It could be the leak is all around since it came out of the valve cover. Or as someone else suggested there is no leak and oil was just spilled all over the cover. I will see if I can eyeball any warping. I guess I'm SOL if that is the case. If so I'll see if I can get it running and just use it as my errand car in town. 


Bottom line is I just shouldn't have taken the mechanic at his word. And done a test first. 

"I can see the gasket is tacked down at a couple of places"
Tacking down just the most critical places of the gasket (against the engine head) is prescribed by many dealer-level docs, hence should be considered normal and acceptable, vs. glueing the gasket to the engine head all-around.

"oil was just spilled all over the cover"
Once-spilled oil attracts small dust and sand particles too fast/soon while driving, and is hardly noticeable after a few days of driving. If dark / oily areas are visible, it is most probably an active leak.

"I will see if I can eyeball any warping"
One cannon eyeball such small deformations. Just place your detached valve cover against a sheet of glass, or mirror, or smth guaranteed to be flat and smooth, and see if there are any non-conformities. As to the engine head warping, I could think of nothing better than placing a steel ruler against the surfaces I could reach - this helped in my case, at least longitudinally.

Well, warping is bad enough, but not cause of the leaks (which you may still fix, and which are mainly cosmetics), but cause it means that your engine head is not even / straight, and this head houses the valves and the mechanics which makes those valves work as they should, and if the head is off this whole mechanics - all those camshafts, rockers, etc. - cannot operate properly inside a deformed engine head, hence will probably die rather sooner than later, without a costy head flatness restoration. Sorry to deliver bad news if this is the case. BTW valve cover (un)flatness is not that critical - as you tighten the screws, a warped cover will usually flatten OK - main thing is that the engine head itself is flat.

"I just shouldn't have taken the mechanic at his word."
I hate the modern world just because of that. One cannot be expected to become The Profi in all professions. And no matter where you go these days - you are with a too high probability just screwed by dishonest persons. In regard to cars, I made my choice and am repairing them myself now to the farthest extent possible. But there are many professions one cannot master as a hobby - like dentist, for example...


Well somehow I broke off ... I'm not seeing how this is considered a DIY job now.


Did you tighten the bolt a few threads in with your fingers, before cranking down with a ratchet?

Did you blow out the bolt hole to make sure there was no liquid or debris inside?


I would just leave the broken one in now. It's only a valve cover.