# Cylinder 4 low compression **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [December 15, 2018, 8:27am UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878 "2018-12-15T08:27:26Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 15, 2018, 8:27am UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/1 "2018-12-15T08:27:27Z")
Hello. We had our toyota yaris timing belt changed yesterday . As soon as we got our car it started idling the garage told us it had a low compression in cylinder 4 fault. The machainic stated that to get it fixed we needed to pay him again. But Before we got the timing chain fixed it never idled shacking now it dose. My question is could the replacing of timing chain be the cause.? ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [December 15, 2018, 9:05am UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/2 "2018-12-15T09:05:08Z")
You need to provide the year model and mileag on the car. You also state on one hand it has a belt and on the other hand it has a chain. It should have a chain. If the chain was worn out that usually means the rest of the engine is also worn out and low compression is a part of that. It could also be that the chain timing is not correct but that should affect all cylinders; not just one. ---
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 15, 2018, 1:46pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/3 "2018-12-15T13:46:43Z")
Its a 2007 toyota yaris it has 105 000 miles on it. We had the timing chain replaced not belt sorry mistake. And the Mechanic stated there is low pressure in cylinder 4 hence the misfire ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [December 15, 2018, 2:40pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/4 "2018-12-15T14:40:23Z")
chains last a long time. does the owners manual say to change timing chain? of course anyone would change the chain if it made noise or rattled as many timing chain tensioners do have issues. many cars have issues with the timing sprockets failing as some control timing advance and are feed by oil pressure. so, why did you change it? ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [December 15, 2018, 2:45pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/5 "2018-12-15T14:45:09Z")
All Yaris’ have a timing chain. If the mechanic installed it improperly, it could have bent a valve in only 1 cylinder before the mechanic corrected it. Impossible to tell from the internet. You need to know why one cylinder is low - rings, bent valve, bad sealing valves. Only one of those 3 might be the mechanic’s fault but hard to say for sure. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [December 15, 2018, 3:28pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/6 "2018-12-15T15:28:36Z")
Why was the chains replaced? Noisy, jumped teeth, broke? A chain that is gone at 105k miles in most cases means the motor oil was not changed often enough and especially if the miles driven involved mostly short hop driving. A 105k miles in 12 years points to light use and that generally means oil changes more often. I would be curious about the compression readings on the other cylinders. If the others are comparatively low then I’d say the engine is prematurely worn out. ---
**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\ **Post date:** [December 15, 2018, 3:55pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/7 "2018-12-15T15:55:46Z")
It’s simple enough to run a leak down test on #4 to see if a valve is the problem. ---
**Author:** ![wentwest](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wentwest/32/6073_2.png) [@wentwest](https://community.cartalk.com/u/wentwest)\ **Post date:** [December 15, 2018, 5:38pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/8 "2018-12-15T17:38:43Z")
I think we need to know why the chain was replaced. ---
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 15, 2018, 5:42pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/9 "2018-12-15T17:42:01Z")
Hello the Machinic said valve cylinder number 4 has low pressure instead of pumping 150 its pumping 50 . We got the timing chain changed because it was rattling. The machanic said we need to.pay more money to get the valve checked again. We have already £600… ---
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 15, 2018, 5:43pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/10 "2018-12-15T17:43:20Z")
Timing chain was rattling and shacking ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [December 15, 2018, 5:43pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/11 "2018-12-15T17:43:23Z")
Yeah, I got that. Re-read my post. it MIGHT be the mechanic’s fault but very hard to pinpoint unless you are looking into the engine and seeing the reason for low compression. ---
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 15, 2018, 5:44pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/12 "2018-12-15T17:44:41Z")
Oh sorry . Yeah thank you fir help ---
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 15, 2018, 5:46pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/13 "2018-12-15T17:46:01Z")
Timing chain was rattling very noisy ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [December 15, 2018, 6:02pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/14 "2018-12-15T18:02:40Z")
car has noisy chain/rattle that mechanic observes prior to job he may also notice a miss or not smooth idle. maybe not replaces chain and noise is gone but now he detects a miss he checks compression and only 1 cyl is low. ---
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 15, 2018, 6:12pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/15 "2018-12-15T18:12:47Z")
Yes he noticed the rattle before fixing . Did the computer test check which showed the timing chain needed changing . Hence the change. But the car did not have idle problem. Which it has now and noise is different from before. ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [December 16, 2018, 2:54pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/16 "2018-12-16T14:54:52Z")
what will he do to fix it? i got the pay him more part. the yaris has a VVT sprocket. was that changed? he is qualified to work on vvt motors? ---
**Author:** ![Helen\_Machemedze](https://avatars.discourse-cdn.com/v4/letter/h/51bf81/32.png) [@Helen\_Machemedze](https://community.cartalk.com/u/Helen_Machemedze)\ **Post date:** [December 16, 2018, 3:25pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/17 "2018-12-16T15:25:43Z")
He just said he will need to remove engine again. Sprockets not changed ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [December 16, 2018, 4:27pm UTC](https://community.cartalk.com/t/cylinder-4-low-compression/130878/18 "2018-12-16T16:27:43Z")
seen this scenario before. noisy timing chain. new parts. low compression. next step is dicey. there was damage all along from loose chain? or botched chain repair?