low compression
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Senior User
Joined: Jul 2009
Posts: 246
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From: Lynnwood, WA
low compression
looks like my truck suffers from low compression. here are the numbers I got after I warmed it up
7=340 8=340
5=360 6=350
3=350 4=340
1=340 2=380
At this point I am not sure if fixing it or just replacing the entire motor with another is a better option. I am going to do a leakdown test to try to find out why were its going.
I have an early 99 so maybe replacing it with the later style would be a good idea. What is all involved in swapping up. I know that the turbo and the airbox is different. Anything else that I will have to concider? Are all the blocks the same?
7=340 8=340
5=360 6=350
3=350 4=340
1=340 2=380
At this point I am not sure if fixing it or just replacing the entire motor with another is a better option. I am going to do a leakdown test to try to find out why were its going.
I have an early 99 so maybe replacing it with the later style would be a good idea. What is all involved in swapping up. I know that the turbo and the airbox is different. Anything else that I will have to concider? Are all the blocks the same?
Posting Guru
Joined: May 2007
Posts: 1,967
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From: Bowling Green, Kentucky
Check out this thread. Your numbers are not good but it should still run for a long time with proper maintenance.
https://www.ford-trucks.com/forums/8...n-numbers.html
https://www.ford-trucks.com/forums/8...n-numbers.html
Post Fiend
Joined: Feb 2007
Posts: 14,541
Likes: 2
From: Dallas-Ft. Worth
Torquing down the injectors & rockers are a very good idea, if it's never been done. Just for grins, I checked one of mine before I pulled the injectors out and it took about a 3/4 turn! Who knows what the rest were. 
The rockers were in pretty good shape -- some required a little more on them, but nothing like the one injector I checked. My new ones are all torqued down to spec now. 
Rockers are 20 ft-lbs, injector hold-down bolts are 120 inch-lbs.
The rockers were in pretty good shape -- some required a little more on them, but nothing like the one injector I checked. My new ones are all torqued down to spec now. Rockers are 20 ft-lbs, injector hold-down bolts are 120 inch-lbs.
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 246
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From: Lynnwood, WA
Torquing down the injectors & rockers are a very good idea, if it's never been done. Just for grins, I checked one of mine before I pulled the injectors out and it took about a 3/4 turn! Who knows what the rest were. The rockers were in pretty good shape -- some required a little more on them, but nothing like the one injector I checked. My new ones are all torqued down to spec now.
Rockers are 20 ft-lbs, injector hold-down bolts are 120 inch-lbs.
The rockers were in pretty good shape -- some required a little more on them, but nothing like the one injector I checked. My new ones are all torqued down to spec now. Rockers are 20 ft-lbs, injector hold-down bolts are 120 inch-lbs.
I think I will pull each of them and check the copper washer and o-rings.
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 246
Likes: 1
From: Lynnwood, WA
Check out this thread. Your numbers are not good but it should still run for a long time with proper maintenance.
https://www.ford-trucks.com/forums/8...n-numbers.html
https://www.ford-trucks.com/forums/8...n-numbers.html
Thread Starter
|
Senior User
Joined: Jul 2009
Posts: 246
Likes: 1
From: Lynnwood, WA
Torquing down the injectors & rockers are a very good idea, if it's never been done. Just for grins, I checked one of mine before I pulled the injectors out and it took about a 3/4 turn! Who knows what the rest were. The rockers were in pretty good shape -- some required a little more on them, but nothing like the one injector I checked. My new ones are all torqued down to spec now.
Rockers are 20 ft-lbs, injector hold-down bolts are 120 inch-lbs.
The rockers were in pretty good shape -- some required a little more on them, but nothing like the one injector I checked. My new ones are all torqued down to spec now. Rockers are 20 ft-lbs, injector hold-down bolts are 120 inch-lbs.
7=350 8=340
5=360 6=380
3=380 4=340
1=355 2=400
decided to not worry about a leak down test until I have enough money to at least do a head job since this is my best case senerio at this point and do some research into what it takes to bring my early 99 to the later version.
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Posting Guru
Joined: Dec 2003
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From: NW Arkansas
Off topic.. butttttt..
I have an complete engine minus start that I wanna go look at.
Could I do a compression test on it by hooking the compression tester up and using a 3/4 in impact on the crank to spin the engine over? I doubt it would show that much pressure but since the impact puts out the same amount of torque each time couldn't I use that to see if all the cylinders are putting out similar pressures?
Thanks and good luck to the OP
I have an complete engine minus start that I wanna go look at.
Could I do a compression test on it by hooking the compression tester up and using a 3/4 in impact on the crank to spin the engine over? I doubt it would show that much pressure but since the impact puts out the same amount of torque each time couldn't I use that to see if all the cylinders are putting out similar pressures?
Thanks and good luck to the OP
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Posting Guru
Joined: Jan 2004
Posts: 1,679
Likes: 0
Off topic.. butttttt..
I have an complete engine minus start that I wanna go look at.
Could I do a compression test on it by hooking the compression tester up and using a 3/4 in impact on the crank to spin the engine over? I doubt it would show that much pressure but since the impact puts out the same amount of torque each time couldn't I use that to see if all the cylinders are putting out similar pressures?
Thanks and good luck to the OP
I have an complete engine minus start that I wanna go look at.
Could I do a compression test on it by hooking the compression tester up and using a 3/4 in impact on the crank to spin the engine over? I doubt it would show that much pressure but since the impact puts out the same amount of torque each time couldn't I use that to see if all the cylinders are putting out similar pressures?
Thanks and good luck to the OP
You might get away with that only if all glowplugs are out. But I doubt that will work very well. Same amount of torque as a starter but the starter is engaging a large gear. . . so the torque at the center of the crank is much higher.
Your compressions aren't horrible. It will smoke on startup. . . especially when cold. But I almost guarantee a leak down will show you its through the rings. With all of them being so close thats a good bet. Change the oil regularly, get a oil bypass kit. . . send out samples then you will really know the condition of every part in your motor.
Last edited by Hiflyer746; Oct 7, 2009 at 07:03 PM. Reason: I love lamp
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
Broke it all down and retorqued the rockers and both injector bolts. all the orings and copper washers looked good. also cleaned out the injector cubs with long q-tips to be sure there was no debris for the washer to sit on. Gave a coupe a boost but didn't get me out of the red.
7=350 8=340
5=360 6=380
3=380 4=340
1=355 2=400
decided to not worry about a leak down test until I have enough money to at least do a head job since this is my best case senerio at this point and do some research into what it takes to bring my early 99 to the later version.
7=350 8=340
5=360 6=380
3=380 4=340
1=355 2=400
decided to not worry about a leak down test until I have enough money to at least do a head job since this is my best case senerio at this point and do some research into what it takes to bring my early 99 to the later version.
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 246
Likes: 1
From: Lynnwood, WA
You own a marginal engine. Checking the compression on a warm engine will also inflate the numbers so if that is the case it is even worse than a cold compression check with the same #s. Did you try adding oil to the cylinders to see if it helped the rings seal and boosted the numbers?
I am guessing as well that its the rings. I don't know for sure what did it but I don't think that I will put a k&n air filter in another vehicle.
Thread Starter
|
Senior User
Joined: Jul 2009
Posts: 246
Likes: 1
From: Lynnwood, WA
Off topic.. butttttt..
I have an complete engine minus start that I wanna go look at.
Could I do a compression test on it by hooking the compression tester up and using a 3/4 in impact on the crank to spin the engine over? I doubt it would show that much pressure but since the impact puts out the same amount of torque each time couldn't I use that to see if all the cylinders are putting out similar pressures?
Thanks and good luck to the OP
I have an complete engine minus start that I wanna go look at.
Could I do a compression test on it by hooking the compression tester up and using a 3/4 in impact on the crank to spin the engine over? I doubt it would show that much pressure but since the impact puts out the same amount of torque each time couldn't I use that to see if all the cylinders are putting out similar pressures?
Thanks and good luck to the OP
Probably best to pull your starter out and throw it in that engine for a test. But from what I have been reading leakdown tests could provide you valuable information and no need to crank the engine.
Thread Starter
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Senior User
Joined: Jul 2009
Posts: 246
Likes: 1
From: Lynnwood, WA