Comments on: 5 Causes of Low Compression in a Car Engine (and How to Fix)

By: J

Mon, 10 Oct 2022 00:25:38 +0000

In reply to Kenny Granville. Yes blue is oil, white is coolant/water

By: Sean

Sean — Thu, 08 Sep 2022 13:44:55 +0000

In reply to Gyan. A leak down test will tell you exactly where you're losing compression. It could be a valve that's not closing properly or worn piston rings, for instance. I'm sure it can be fixed. Hard to say how much it will cost to fix without knowing the exact problem, but it probably won't be cheap.

By: Gyan

Gyan — Thu, 08 Sep 2022 00:40:21 +0000

In reply to autotechnician. I have audi A3 2008 2T, there is no compression in the 2nd cylinder, other 3 cylinder is fine. It is shaky when you drive and does not take pick up more than 25-35. what can be the issue. can it be fixed ? How much it will cost to fix it.

By: Sean

Sean — Thu, 07 Apr 2022 16:00:54 +0000

In reply to Kristin.

Where did they find the rodent nest? Was it in the air intake or elsewhere in the engine bay?

I think it’s extremely unlikely that a rodent infestation could cause low compression. The valves in an engine don’t open up very far; certainly not far enough for a rodent to crawl into the combustion chamber.

The only way I could think of this conceivably happening is if rodents made their way into the air intake past the air filter. If they put nest material in the intake and this material made its way into the engine, this could cause low compression as the nest material wears against the pistons, rings, and cylinder walls. If this is the case, it should be pretty easy for the dealership to determine if they are tearing down the engine, though.

This possibility of this happening is not proof that it happened, though. I think the engine expert who is coming out should be able to determine or rule out this possibility. Ask them to take pictures of the air intake and combustion chamber so you can see for yourself.

What were the numbers from the compression test?

By: Kristin

Kristin — Wed, 06 Apr 2022 03:29:19 +0000

Thanks so much for posting your very informative videos. PLEASE HELP!!! I will start with the question I am hoping you can answer, explain the backstory and end with the same question to keep things organized. I genuinely appreciate any advice and feedback you can offer. Do you think it is possible for a rodent nest (10″x6″ mind you!!) to cause no compression in cylinder 5? I have an expensive problem on my hands. I was driving my 2015 Toyota Highlander (102, 000 miles well maintained with proof of service) it started shaking and check engine light, Check all wheel drive and check traction lights came on. Brought it to our local mechanic and they found a rodent nest on the engine (engine bay I believe), upon further inspection they found that cylinder 5 had no compression, but they weren’t exactly sure why and suggested we take it to the Toyota dealership for additional diagnostic. They found the same issue (still don’t know why, but they don’t seem to think it could be rodent related, but again aren’t certain what caused the issue). Because there is no other reason given, do you think it is possible that it could be rodent related? It just seems very coincidental, but because I don’t know enough about cars it is hard for me to prove although I am trying to dig up what I can and found you 🙂 Toyota and the insurance company didn’t see any obvious wire chews so they closed my claim saying it must be “wear and tear” except I have our steady service records and the mileage is less than a standard lease contract- we have a 2010 Rav 4 with 30,000 more miles that is serviced the same and is running great- the mechanics said this is “very rare for a 2015 Toyota” and said I essentially got the short stick and that cars break, and now I was forced to replace the engine as the only solution ($8,200 +450 in diagnostic fees). Toyota was hoping they would find an actual reason (and of course I was hoping it was rodent related as it would be covered by insurance), but they took out the engine and still have no distinct reason for the engine failure/ cylinder misfire, but said maybe it could be debris that made it way into the engine somehow or a mechanical issue (broken arm??). Anyway because that differs from chewed wires, I reopened the claim thinking it could potentially be nest material (there was lots of material) or mouse food “debris”- there just isn’t another explanation at this point. My family has been without our vehicle for almost 1 month and it has really made our lives difficult. Anyway, sorry for the long story, but the insurance company is sending out a “engine expert” tomorrow morning to look at the engine and prob try to disprove that it could be rodent related and it feels like it is my last chance to make a connection and prove that it is possible. I found some articles that say maybe an issue or obstruction in the intake?/ debris somehow getting by the air filter and clogging or making its way into the cylinder?/ debris getting sucked into the air filter then the intake (intake runners or intake manifold)?/ Debris getting caught in the valve train preventing the valves from closing causing no compression?/ a block in the throttle plates??/ Issue with the knock sensor injector?? I will ask more questions tomorrow, do you have any advice on how the rodent nest could have caused no compression in cylinder 5? Thank you in advance, Kristin

By: Sean

Sean — Fri, 04 Jun 2021 15:36:39 +0000

In reply to Kenny Granville. No, most of the time it's dark and has a bluish tint. White smoke is usually coolant.

By: Kenny Granville

Kenny Granville — Fri, 04 Jun 2021 13:32:41 +0000

In reply to autotechnician. If your burning OIL from your engine the smoke out of your exhaust will be WHITE

By: Austin

Austin — Thu, 29 Apr 2021 04:26:42 +0000

In reply to Joseph. 2018 F-150 Limited 3.5L 6V Gas

By: Sean

Sean — Wed, 06 Jan 2021 15:45:03 +0000

In reply to Sean.

You can do a leak down test to determine where you are losing compression. Once you know where the leak is coming from, a mechanic can give you a quote on what it will cost to fix and you can determine what you want to do with your engine.

For more involved repairs like valve jobs, head gasket replacements, and engine rebuilds, many people will pay a mechanic to have the work done. Some people will opt to put a new engine in their car to keep the car on the road (and sometimes you can swap to a more powerful engine). Many are fed up with their car breaking down and go buy a new one. A few will just drive the car into the ground and do nothing.

You will have to determine what is best in your specific situation based on the problem that is discovered, your budget, and your use case for the vehicle.

By: Sean

Sean — Tue, 05 Jan 2021 22:56:26 +0000

I have low compression in 1 and 5. Any advice?