Engine runs, low compression?

[Knownothing]

Hey guys I am new and this is my first time dealing with a 6.5 turbo. A friend of mine has one and he had an issue with the torque convertor not locking up going down the road. Transmission went out so he put a new one in and it did the same thing. They diagnosed it and found that it needed an injection pump. Installed new pump and he was told that the pickup was done. Dropped it off and was informed that the pickup now had low compression. Is there an adjustment on the pump that would make it run like it has low compression or should we be looking at a rebuild. Any info would be greatly appreciated. Thanks

 

[dbrannon79]

Welcome to the forum. there are not that many shops that "know" these engines and even fewer that "know" the 4l80e trans. At least good reliable shops that won't take your $$ and run! it sounds like you need to pick it up and do some diagnosing like a compression test to see the actual numbers. an IP won't cause the trans to not actuate the TCC other than the sensors that are on it giving faulty readings..

fill out your signature with your truck details. others will chime in with some diagnostic procedures and were to start first.

there are lots of knowledgeable folks here with a vast amount of info that will help you.

 

[jrsavoie]

Did they do a compression test?

What is the actual compression on each cylinder?

If they didn't do a compression test they could just be talking out their butt.

 

[dbrannon79]

If yours is a 94+ that has the DS4 electronic injection pump, these are no longer offered as "NEW" there are no more in production and only rebuilds available. it's very possible that they installed the IP and not timed properly. there are only a couple of scanners that are capable of setting timing. one being the GM tech 2. the only other one I'm aware od is the GMTDscan software on a laptop. the Snap-ON scanner does not give accurate readings for these trucks with 6.5 diesels.

 

[Will L.]

Holy moly- run don’t walk from that shop.
Best thing to do is get a video, post on YouTube or similar then put the link here.

The knowledge of the the guys on this forum will get any issue solved.

Low compression has to be AMAZINGLY low to not run right. And the fact that he could tell the tc was not locking up means he had enough compression to start and get up to 45 mph. When compression is really bad it will burn oil, but even that has some fixes to keep it on the road.

Since shop changed the ip (injection pump) it is possible they didn’t set it up right. What year, and other details like 2500 or G30 the truck is comes into play.
Basically we need more info as to what EXACTLY the problem is with how it is driving right now? Are there and engine codes and if so what are they? Any paperwork from the shop- post pics of.

 

[MrMarty51]

Welcome to the forum.
If the compression is that bad, there will be boookooo blow by.
If the engine runs at all, remove the oil fill cap and see how much smoke blows out the filler pipe.
Posting a video, of the blow by, needs to be posted into youtube or some other hosting site and then the link provided here.
The people in the know can then watch the video and make some determinations and suggestions.

 

[Knownothing]

Welcome to the forum.
If the compression is that bad, there will be boookooo blow by.
If the engine runs at all, remove the oil fill cap and see how much smoke blows out the filler pipe.
Posting a video, of the blow by, needs to be posted into youtube or some other hosting site and then the link provided here.
The people in the know can then watch the video and make some determinations and suggestions.

Ok. It's been sitting for a while and the batteries are shot. He is going to get batteries for it and start it sometime in the next couple of weeks.

 

[Knownothing]

Truck is a 94 single cab with the 8th or 9th digit being an F

 

[Knownothing]

Holy moly- run don’t walk from that shop.
Best thing to do is get a video, post on YouTube or similar then put the link here.

The knowledge of the the guys on this forum will get any issue solved.

Low compression has to be AMAZINGLY low to not run right. And the fact that he could tell the tc was not locking up means he had enough compression to start and get up to 45 mph. When compression is really bad it will burn oil, but even that has some fixes to keep it on the road.

Since shop changed the ip (injection pump) it is possible they didn’t set it up right. What year, and other details like 2500 or G30 the truck is comes into play.
Basically we need more info as to what EXACTLY the problem is with how it is driving right now? Are there and engine codes and if so what are they? Any paperwork from the shop- post pics of.

Ok. I'll get some more information for you. He was able to drive it to his farm because he was going to hook up to a trailer with it but once he got there he didnt have enough power to back under the trailer. It's a 94 with an F in the vin

 

[TOBASH]

Many unknowns.

Need to know injection pump type. DB2 vs DS4. Need a copy of mechanics receipt showing type of injection pump they replaced/installed.

Need to know compression numbers for each cylinder. Measuring compression is easy with the correct tools. You guys can do it if the mechanic didn’t BUT why would a mechanic work on a rig to replace an IP before checking compression. If you have bad compression you can successfully sue him for negligence if he replaced an IP a in an otherwise bad engine. Maybe HE didn’t reattach the intake manifold properly and maybe he is responsible for the issue?

A video showing engine AND exhaust while running. That will show us if there is “blow-by”.

Is the engine original to the truck or is it a replacement engine?

Need to know oil level and if he needs to “top off” the oil frequently. In other words, is he burning oil?

Need to know if tranny had burnt fluid or if it is requiring fluid due to leaks. Check the fluid for metal shavings and color and odor. Does it smell burnt?

Just my simple suggestions to start.

If you’re in farm country, find a mechanic that works on diesel trucks used in trachter pulls.

 

[TOBASH]

EDIT-Tractor.

 

[Rockabillyrat]

With modern amp ramping technology a well equipped shop should be able to do a compression check in less than 5 mins. That's my preferred method, If I see and issue on the scope then I bust out the manual gauge.

At this point if the repair shop didn't give you each cylinders compression numbers then you have to start with measuring that first and go from there. Modern diesel techs are spoiled by being about to do compression checks with scan tools. So when they get these old IDIs in the shop they tend to forget the basics and throw parts at it. You would be surprised how many techs cant work on these engines.

If it does have low compression it should smoke heavily on start up and have excessive crank case pressure. Usually its really easy to tell when you have a low compression issue.