Hi, I have a 2014 Land Rover Discovery 4 (Diesel). A couple of months ago, while I was driving on the highway, just going up a slope, the car suddenly turned off. The mechanics at the workshop concluded that it was an injection problem, so all the injectors were replaced. Now, with the new injectors, the mechanic discovers low compression. The compression values are as follows:

cylinder 1 - 150 PSI

cylinder 2 - 125 PSI

cylinder 3 - 115 PSI

cylinder 4 - 160 PSI

cylinder 5 - 140 PSI

cylinder 6 - 120 PSI

The mechanic put oil in the cylinders, and it does not raise the compression, which, he tells me, indicates that it is not a ring problem.

Does anyone have any idea what could be the cause of the problem?

 

There are only so many things that can cause low compression, head gasket likely the most common. Leak-down test should tell you where the compression leak is at. The odd thing is that it looks like you’ve got it on both banks (cylinders 2, 3, and 6), so you’d have to blow both head gaskets at once. If you lost a timing chain/belt, you could have bent some valves on both sides.

I’m wondering if he didn’t install your injectors properly, and compression is blowing out around the seals. Also, why did he think it was injectors in the first place?

 

Hi, thank you very much for your comment. I must say that my knowledge of mechanics is limited. However, with your response, I decided to study the Leak-down test and all the information it provides. As far as I know, they have not done this test at the workshop.

I also don't know why they did the replacement of the injectors. The mechanic only said that the original ones were damaged, and the replacement of the injectors had a significant cost (approx. 3500 usd). Now they tell me that the car is not running due to a compression problem and suggest that they have to disassemble the whole motor. I decided to raise my concern in this forum to clarify what to expect... or to define if it is pertinent that I take the car to another workshop. I will ask them to perform a leak test to see what information it gives. I will let you know the results.

Thank you very much.