7.3L Compression test: questions?????
Thread Starter
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Posting Guru
Joined: Mar 2008
Posts: 1,537
Likes: 0
From: Dongola, IL
I just did the compression test, here are the results:
1-321.5
2-333.5
3-294
4-312.5
5-78.5
6-315.5
7-312
8-335
Number 5 seems to be the biggest problem
What would you guys recommend as my next step?
1-321.5
2-333.5
3-294
4-312.5
5-78.5
6-315.5
7-312
8-335
Number 5 seems to be the biggest problem
What would you guys recommend as my next step?
Thread Starter
|
Posting Guru
Joined: Mar 2008
Posts: 1,537
Likes: 0
From: Dongola, IL
Well, the owner of the truck and I decided that whether it was a valve or ring problem, it would not make sense to sink a bunch of money into a motor that has at best fair compression. So, he is finding another motor to put in it.
I will be changing it for him, and probably will have more questions later.
Thank you everyone for answering my questions, it is very helpful!!
I will be changing it for him, and probably will have more questions later.
Thank you everyone for answering my questions, it is very helpful!!
Post Fiend
Joined: Apr 2004
Posts: 12,835
Likes: 3
From: Silver Lake Dunes, MI
Well, the owner of the truck and I decided that whether it was a valve or ring problem, it would not make sense to sink a bunch of money into a motor that has at best fair compression. So, he is finding another motor to put in it.
I will be changing it for him, and probably will have more questions later.
Thank you everyone for answering my questions, it is very helpful!!
I will be changing it for him, and probably will have more questions later.
Thank you everyone for answering my questions, it is very helpful!!
New User
Joined: Dec 2016
Posts: 2
Likes: 0
Low compression, one cylinder
Took my sons 94 F250 (7.3 turbo diesel) in to the shop because she has a super rough idle and some white smoke coming out of the tail pipe. Shop said they replaced the bad fuel injector but it did not resolve the problem. They did a compression check and said that particular cylinder is bad (150psi) and proceeded to tell me that the engine is toast. He did not do the compression check on the rest. He also told me that it would be a very expensive repair especially if it needed to be rebuilt or a new/reman dropped in.
I talked to my ex-husband (who is a diesel mechanic) and he said that it could be bad piston rings or bad valve. I did not ask for his help on this issue other than asking for his opinion (he just takes too darn long to fix things). My son is still making payments on this truck (he bought it on his own without any help in getting financing) and would prefer to get this baby fixed rather than making payments on something he can no longer drive.
Question is......what would the ballpark cost be if its just a broken ring?
(My son really blows up when he does not like the answers I get from the mechanics at the shop.)
In the meantime, I will look for a reman for his rig. Hopefully I'll find something affordable and someone reasonably affordable to drop it in.
Knowing my son, he'll drive her until she blows up.
I talked to my ex-husband (who is a diesel mechanic) and he said that it could be bad piston rings or bad valve. I did not ask for his help on this issue other than asking for his opinion (he just takes too darn long to fix things). My son is still making payments on this truck (he bought it on his own without any help in getting financing) and would prefer to get this baby fixed rather than making payments on something he can no longer drive.
Question is......what would the ballpark cost be if its just a broken ring?
(My son really blows up when he does not like the answers I get from the mechanics at the shop.) In the meantime, I will look for a reman for his rig. Hopefully I'll find something affordable and someone reasonably affordable to drop it in.
Knowing my son, he'll drive her until she blows up.
Cargo Master
Joined: Nov 2009
Posts: 2,560
Likes: 20
Took my sons 94 F250 (7.3 turbo diesel) in to the shop because she has a super rough idle and some white smoke coming out of the tail pipe. Shop said they replaced the bad fuel injector but it did not resolve the problem. They did a compression check and said that particular cylinder is bad (150psi) and proceeded to tell me that the engine is toast. He did not do the compression check on the rest. He also told me that it would be a very expensive repair especially if it needed to be rebuilt or a new/reman dropped in.
I talked to my ex-husband (who is a diesel mechanic) and he said that it could be bad piston rings or bad valve. I did not ask for his help on this issue other than asking for his opinion (he just takes too darn long to fix things). My son is still making payments on this truck (he bought it on his own without any help in getting financing) and would prefer to get this baby fixed rather than making payments on something he can no longer drive.
Question is......what would the ballpark cost be if its just a broken ring? (My son really blows up when he does not like the answers I get from the mechanics at the shop.)
In the meantime, I will look for a reman for his rig. Hopefully I'll find something affordable and someone reasonably affordable to drop it in.
Knowing my son, he'll drive her until she blows up.
I talked to my ex-husband (who is a diesel mechanic) and he said that it could be bad piston rings or bad valve. I did not ask for his help on this issue other than asking for his opinion (he just takes too darn long to fix things). My son is still making payments on this truck (he bought it on his own without any help in getting financing) and would prefer to get this baby fixed rather than making payments on something he can no longer drive.
Question is......what would the ballpark cost be if its just a broken ring?
(My son really blows up when he does not like the answers I get from the mechanics at the shop.)In the meantime, I will look for a reman for his rig. Hopefully I'll find something affordable and someone reasonably affordable to drop it in.
Knowing my son, he'll drive her until she blows up.
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New User
Joined: Dec 2016
Posts: 2
Likes: 0
Thinking I'll call the Diesel Instructor (since I know him) up at our local college to see if he can help. Maybe the students this year needs a project to do. Can't afford to take it to another shop for a second opinion.
I'd do the test myself but I'd probably screw something up.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
Is this a PSD? What are the 8th and 10th positions of the VIN?
Generally, I would be very doubtful of the word of a "mechanic" who compression tests only one chamber, let alone one who makes any diagnosis based on testing just one.
Generally, I would be very doubtful of the word of a "mechanic" who compression tests only one chamber, let alone one who makes any diagnosis based on testing just one.
Fleet Mechanic
Joined: Nov 2006
Posts: 1,954
Likes: 1
From: Knoxville, TN
^^ditto....need to see how that one cylinder compares to the other to see if it is an overall wear issue or something isolated to that one cylinder...
Makes you wonder if "the mechanic" properly torqued down the injector before doing said test....I know my two cylinders that were lower on compression had bolts that were a lot easier to get out...aka not torqued down properly...
