Can you use RTV silicone to patch a hole in a timing belt cover?
Using RTV silicone can temporarily cover a small hole in an engine cover to keep out dirt and rocks, provided it can withstand the engine's heat. However, on a brand-new motor with low mileage, applying a quick patch carries the risk of material melting or failing, which leaves the critical belt vulnerable to damaging debris.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 17.4× more often in r/AskMechanics than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Applying RTV silicone over the holeDid this help you?
- 2Using marine epoxy puttyDid this help you?
- 3Covering the hole with duct tapeDid this help you?
- 4Using a piece of plastic with epoxyDid this help you?
- 5Plastic welding the coverDid this help you?
- 6Temporarily covering the opening with a makeshift cover so rodents and debris do not fall inDid this help you?
- 7Applying bleach to shock the well to prevent contamination from kicked-up debrisDid this help you?
- 8performing a complete teardown to inspect internal componentsDid this help you?
- 9replacing the engine entirelyDid this help you?
- 10using brake clean, WD40, and fogging oil to protect cylinders instead of neutralizing acidDid this help you?
- 11hoping that honing will be sufficient instead of a full boreDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Have a truck that hydro-locked and broke the #7 connecting rod. It's currently seized against the block. My question is should I replace the other piston that got minor dings in it as well as the one that broke? Or is this whole deal just a throwaway at this point?”source ↗
“i have this hole in my timing belt cover if i put RTV silicone would i be okay or would i need to replace the whole cover ?”source ↗
“this is a new motor with less than 30k miles i dont want to ruin the engine”source ↗
“would it be able to withstand the heat coming from the engine because i don’t want it to melt off”source ↗
“okay i see now because i don’t want dirt and rocks to get into my belt it’s brand new”source ↗
“yeah for sure that’s the last thing i need and the hole isn’t to big so i just wanted to see if i can put something on there to cover the hole to keep out dirt and etc”source ↗
“Unfortunately my wallet is going to be feeling much lighter, and it’s time to support my local automotive machine shop :D, one can only hope honing will be enough and I don’t need a bore.”source ↗
“Fingernail catches badly on it, I was attempting a budget restoration with the intention of having something somewhat reliable and fun on the other side.”source ↗
“After 10 years in this house, I finally did it. None of the wiring looks damaged but this cap seems about impossible to remove.”source ↗
Where this came up
People with this problem also raised
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