Hello and welcome to the latest from The Toolbox.
This post deals with a no start issue on a 2007 Maxforce DT. In other words, a DT466 EGR motor. The truck was towed in and the word was that it wouldn't start for the owner on Monday morning. The owner also stated he thought it was a fuel problem, specifically that it had “lost prime”. It’s always great when a clairvoyant owner offers his diagnosis of a problem! I had done a camshaft replacement on this truck a little over a year previously, and then a set of injectors after two of them failed in a two week period. One of the first shift guys started to check out the problem, and stated the truck started fairly well for him and that the fuel pressure was to spec.
The owner wanted an oil change and DOT inspection while the truck was in, and I figured changing oil and filters was a good place to start. The owner is one of those “fuel it and forget it” guys: the only time we saw the truck was when it wouldn't run. There was no telling when the oil had last been changed, and oil that is too thin due to age, dilution, or improper viscosity can cause starting problems in a DT. First I checked that the old oil was at the proper level and seemed free from fuel dilution.
After the service the truck would start, but only after about 10 seconds of cranking, and didn't build rpm properly nor did it reach high idle in neutral. Hooking up the laptop showed the ICP (injection control pressure) built OK during crank, but a code was set for low fuel pressure, along with an inactive code for low injection control pressure during cranking. Hooking up a gauge to check fuel pressure showed 0 indicated fuel pressure while the engine was running, and would only build to about 5 psi at higher rpm against a spec of 60-70 psi at idle. A bad fuel pump was a possibility, but much more likely was a stuck regulator or outlet check valve. The fuel pressure regulator and outlet check valve are both in the fuel bowl on this engine. The outlet tube is about an inch and a half above the bottom of the bowl, and the pressure regulator sits in a tube extending about an inch above the bottom. I have to admit that I didn't look into the fuel bowl when I changed the filter but I did now, and saw a lot of debris in the bottom of the bowl. When I poured fuel into the bowl, it drained down instantly to the level of the outlet, so obviously the outlet valve was stuck open.
According to the local dealer, parts to service the regulator are no longer available; the only option is to replace the filter assembly. The assembly came complete including a filter, sensor, and heater, so replacement was simple. Once the fuel system was primed and the air bled out, the engine started immediately several times, so I figured the problem was solved. A test drive went well and the truck restarted afterwards, but I wanted to let the truck sit and heat sink awhile and then see how it started and ran. I try to follow this procedure whenever I have repaired a unit where the symptoms are ambiguous or sketchy and it was good I did it this time, as the truck would not start after sitting 20 minutes. I hooked up the laptop and found it setting an active code for low ICP pressure during cranking.
After the truck cooled off for an hour it again started immediately and the data monitor screen showed good response from the ICP sensor, so it now looked like I had a second problem, possibly a leak in the high pressure oil system. These problems often lead to a no start hot, when the oil gets thinner. While messing around on the laptop checking out sensor outputs, I found that as when the oil temperature reached 150 degrees the engine would fail to start, not building sufficient injection control pressure.
Before thinking about a leak in the high pressure system, you first need to make sure the pump is able to make sufficient pressure. One of the most important diagnostic tools for anyone working on HEUI engines is a pressure gauge of at least 5000 psi capacity connected to a hydraulic hose a couple of feet long. The high pressure pump feeds engine oil to the high pressure manifold through a hose. Just unscrew the hose from the head fitting in EGR motors or from the oil rail on older engines, and hook the gauge to the hose. An adapter must be used between the pump hose and your gauge hose. I made one for the EGR application by drilling a hole through a metric drain pan plug, threading the hole for my gauge hose, and screwing the oil line swivel onto it. A copper seal, like a large brake caliper hose seal, can be used to seal the connection. The pump regulator must be hooked to battery voltage so the pump will make maximum pressure. Get a pigtail for the regulator from your local IH dealer, unhook the harness connection from the regulator, and plug in your diagnostic connector. The regulator is magnetic, so it doesn't matter which you hook up to power or ground, but do not leave it hooked up for more than a minute at a time or the regulator will burn up. Have a helper crank the engine over for a few seconds and watch the gauge. On EGR motors, the pump should make its maximum 5000 psi almost immediately. If not, either the regulator or the pump is bad. As a new OEM pump comes with a new regulator, I just replace the pump.
Someone reading this will surely Email me and say that the proper procedure is to replace the regulator and if that doesn't help, then replace the pump. The problem is that once you have installed the regulator it can’t be returned for credit, so I feel you may as well just replace the pump and be done with it. I personally have never seen a new regulator fix a low pressure problem, anyway.
The engine I was working on passed the test, so I was now looking for a leak in the high pressure oil system. Actually, changes made for the EGR version of the DT engine have given oil fewer places to leak. Moving the oil rail from the side of the block to above the injectors means oil will no longer mix with fuel when injector O-rings fail, and there is no gasket to leak oil down the side of the block. Assuming the injectors themselves don’t leak, the only place for a high pressure leak is from the seals on the oil rail. Each injector is sealed to the oil rail by an O-ring backed up by a nylon spacer. The seal set includes three different thicknesses of spacers, and which is installed depends on the dimension of the O-ring groove. The problem is that you can’t see what’s leaking with the manifold in place, and according to ISIS there are non-serviceable O-rings inside the manifold. There is always some oil leaking down the tops of the injectors in a running engine, but there seemed to be a lot of it on this one.
To try to find exactly where the leak was, I used the same adapter I used to check the pump output, and put it in the pump end of the output hose. When I applied shop air to the hose, air could be felt and heard from above at least the front 5 injectors. If the system leaked at 150psi, it’s no wonder the engine wouldn't start hot. I was surprised it ran at all. I tried a new set of oil manifold seals, but the results were the same. The width of the O-ring groove called for the medium thickness spacer behind the O-ring, but I re-installed the seals with the thick spacers just to see if that would help. It didn't. Luckily at the same time another truck with the same engine came in with a failed injector, so I was able to try the oil manifold from that one on the problem engine. With the time I already had into this job, I had to be sure of the correct diagnosis. When the engine was run to temperature with the new manifold in place it still failed to start, so the problem had to be the injectors. This engine had a new set of injectors just over a year before, which was one of the reasons for my problem with this diagnosis.
With the manifold back off, I cleaned the injector oil ports out and could see a wear pattern made by the O-rings, and could use a pick to actually feel a small ridge there. I conclude that the extended oil change intervals may have contributed to the problem. Anyway, a new set of injectors was installed and the engine fired and ran instantly at all temperatures. Several sources I have read blame DT injector failures on dirty oil and/or excessive change intervals, and this instance might point out the extent of problems caused by those situations.
Well, thanks for reading this post, check back for more soon.
An additional note: click on the DT466E No Start tab above the posts to go to the sales point for my No Start Diagnostic book.
Bruce Christopherson
This post deals with a no start issue on a 2007 Maxforce DT. In other words, a DT466 EGR motor. The truck was towed in and the word was that it wouldn't start for the owner on Monday morning. The owner also stated he thought it was a fuel problem, specifically that it had “lost prime”. It’s always great when a clairvoyant owner offers his diagnosis of a problem! I had done a camshaft replacement on this truck a little over a year previously, and then a set of injectors after two of them failed in a two week period. One of the first shift guys started to check out the problem, and stated the truck started fairly well for him and that the fuel pressure was to spec.
The owner wanted an oil change and DOT inspection while the truck was in, and I figured changing oil and filters was a good place to start. The owner is one of those “fuel it and forget it” guys: the only time we saw the truck was when it wouldn't run. There was no telling when the oil had last been changed, and oil that is too thin due to age, dilution, or improper viscosity can cause starting problems in a DT. First I checked that the old oil was at the proper level and seemed free from fuel dilution.
After the service the truck would start, but only after about 10 seconds of cranking, and didn't build rpm properly nor did it reach high idle in neutral. Hooking up the laptop showed the ICP (injection control pressure) built OK during crank, but a code was set for low fuel pressure, along with an inactive code for low injection control pressure during cranking. Hooking up a gauge to check fuel pressure showed 0 indicated fuel pressure while the engine was running, and would only build to about 5 psi at higher rpm against a spec of 60-70 psi at idle. A bad fuel pump was a possibility, but much more likely was a stuck regulator or outlet check valve. The fuel pressure regulator and outlet check valve are both in the fuel bowl on this engine. The outlet tube is about an inch and a half above the bottom of the bowl, and the pressure regulator sits in a tube extending about an inch above the bottom. I have to admit that I didn't look into the fuel bowl when I changed the filter but I did now, and saw a lot of debris in the bottom of the bowl. When I poured fuel into the bowl, it drained down instantly to the level of the outlet, so obviously the outlet valve was stuck open.
According to the local dealer, parts to service the regulator are no longer available; the only option is to replace the filter assembly. The assembly came complete including a filter, sensor, and heater, so replacement was simple. Once the fuel system was primed and the air bled out, the engine started immediately several times, so I figured the problem was solved. A test drive went well and the truck restarted afterwards, but I wanted to let the truck sit and heat sink awhile and then see how it started and ran. I try to follow this procedure whenever I have repaired a unit where the symptoms are ambiguous or sketchy and it was good I did it this time, as the truck would not start after sitting 20 minutes. I hooked up the laptop and found it setting an active code for low ICP pressure during cranking.
After the truck cooled off for an hour it again started immediately and the data monitor screen showed good response from the ICP sensor, so it now looked like I had a second problem, possibly a leak in the high pressure oil system. These problems often lead to a no start hot, when the oil gets thinner. While messing around on the laptop checking out sensor outputs, I found that as when the oil temperature reached 150 degrees the engine would fail to start, not building sufficient injection control pressure.
Before thinking about a leak in the high pressure system, you first need to make sure the pump is able to make sufficient pressure. One of the most important diagnostic tools for anyone working on HEUI engines is a pressure gauge of at least 5000 psi capacity connected to a hydraulic hose a couple of feet long. The high pressure pump feeds engine oil to the high pressure manifold through a hose. Just unscrew the hose from the head fitting in EGR motors or from the oil rail on older engines, and hook the gauge to the hose. An adapter must be used between the pump hose and your gauge hose. I made one for the EGR application by drilling a hole through a metric drain pan plug, threading the hole for my gauge hose, and screwing the oil line swivel onto it. A copper seal, like a large brake caliper hose seal, can be used to seal the connection. The pump regulator must be hooked to battery voltage so the pump will make maximum pressure. Get a pigtail for the regulator from your local IH dealer, unhook the harness connection from the regulator, and plug in your diagnostic connector. The regulator is magnetic, so it doesn't matter which you hook up to power or ground, but do not leave it hooked up for more than a minute at a time or the regulator will burn up. Have a helper crank the engine over for a few seconds and watch the gauge. On EGR motors, the pump should make its maximum 5000 psi almost immediately. If not, either the regulator or the pump is bad. As a new OEM pump comes with a new regulator, I just replace the pump.
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| tools for HEUI diagnosis: 5000psi gauge & hose, fittings, and pigtail to deadhead pump. |
Someone reading this will surely Email me and say that the proper procedure is to replace the regulator and if that doesn't help, then replace the pump. The problem is that once you have installed the regulator it can’t be returned for credit, so I feel you may as well just replace the pump and be done with it. I personally have never seen a new regulator fix a low pressure problem, anyway.
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| 466 DT high pressure oil components |
To try to find exactly where the leak was, I used the same adapter I used to check the pump output, and put it in the pump end of the output hose. When I applied shop air to the hose, air could be felt and heard from above at least the front 5 injectors. If the system leaked at 150psi, it’s no wonder the engine wouldn't start hot. I was surprised it ran at all. I tried a new set of oil manifold seals, but the results were the same. The width of the O-ring groove called for the medium thickness spacer behind the O-ring, but I re-installed the seals with the thick spacers just to see if that would help. It didn't. Luckily at the same time another truck with the same engine came in with a failed injector, so I was able to try the oil manifold from that one on the problem engine. With the time I already had into this job, I had to be sure of the correct diagnosis. When the engine was run to temperature with the new manifold in place it still failed to start, so the problem had to be the injectors. This engine had a new set of injectors just over a year before, which was one of the reasons for my problem with this diagnosis.
 |
| a diagnostic pigtail replaces the engine connection to test the pump |
With the manifold back off, I cleaned the injector oil ports out and could see a wear pattern made by the O-rings, and could use a pick to actually feel a small ridge there. I conclude that the extended oil change intervals may have contributed to the problem. Anyway, a new set of injectors was installed and the engine fired and ran instantly at all temperatures. Several sources I have read blame DT injector failures on dirty oil and/or excessive change intervals, and this instance might point out the extent of problems caused by those situations.
Well, thanks for reading this post, check back for more soon.
An additional note: click on the DT466E No Start tab above the posts to go to the sales point for my No Start Diagnostic book.
Bruce Christopherson
2 comments:
Regarding the fuel system components: you were unclear whether this was a Maxxforce DT or a DT466 EGR. The pictures indicate that it is a DT466 EGR. Fuel pressure regulators are available for either engine. The difference between the two is that the DT466 EGR engine does not have a fuel return to the tank, The Maxxforce DT does have a return to the tank. The older, non-EGR DT had a fuel pressure regulator on the fuel rail at the back of the head, which went back to the tank. If we are talking about an EGR DT, it is critical to inspect the fuel filter housing for debris. The check valve in the fuel pump will sometimes come apart and end up in the fuel filter housing. You will notice the spring metal and pieces of the white plastic poppet lying in the bottom of the housing during a fuel filter change. It is a good bet that the fuel pump will need to replaced in this situation (there was a recall on these engines for this situation). As far as "No-start when hot" situations, this usually indicates an ICP leak under the valve cover, mostly high pressure oil rail O-rings. This is not a "silver bullet" for diagnosis however. One must start at one end of the system and work their way up to the HP rail. Base engine oil pressure is first. If the engine is slow to build base EOP, then the high pressure pump doesn't have a chance to do it's job. It doesn't take much-if you have 3-5PSI of bas oil pressure during cranking, that is enough to supply the high pressure oil pump. A quick check to verify this is to remove the oil temp sensor in the front cover. That area of the front cover is a reservoir that the high pressure pump uses to draw from. If oil does not spill out upon removing the sensor, you need to troubleshoot base oil pressure. Assuming you have an oil supply to the high pressure pump, you need to "full field" the IPR valve (regulator on the pump). If you apply 12v directly to the IPR (taking the ECM control out of the equation) and crank the engine, and still get low ICP on the laptop, then we need to verify the high pressure pump and regulator's ability to produce pressure. Removing the hose from the cylinder head, or using a test hose directly off the pump, with a 0-10,000 PSI gauge, apply 12v to the IPR and crank the engine. An EGR DT pump should produce 5000+ PSI. A Maxxforce DT should make 6000+. If this checks out then you have a leak under the valve cover. If the results are under those numbers, then you have a problem with either the pump or the IPR. There is a tool to thread into the pump that will bypass the IPR and cause the pump to produce maximum pressure. You can purchase the tool from an International dealer. If you install the tool and gain pressure, then the IPR is at fault. Replace it and re-test. Otherwise, if you full field the
IPR and get good pressure on the gauge, then remove the valve cover, unplug all 6 injectors, full field the IPR again, and crank the engine. Sending 5000-6000PSI up to the rail will indicate a leak. Repair accordingly and retest. There are 3 causes of under-valve cover leaks: high pressure rail O-rings, oil inlet adapters (pucks), or the injectors themselves. I recommend removing the rail once a leak is identified, if the orings are intact, replace the pucks and retest. If there are still leaks, then replace the injector(s). If the rail orings are failed, then reseal the rail and retest. Just my 2 cents.
Thanks for those tips,Cking. Much of what you said was covered in some of my earlier posts, but you covered well some of the necessary steps I bypass as assumed. For instance, I assume that in checking for an ICP leak that the base oil pressure is present, and that the high pressure reservoir is getting oil.
One reason I bypass some of the basics is that I am trying to give an overview of a particular solution instead of a step-by-step process. I feel that proper diagnostic software is an absolute necessity in diagnosing modern engine problems, and that anyone with access to those tools also has the knowledge to do the basics. That may be an assumption I shouldn't make.
As to the difference between the DT EGR and Maxxforce DT engines, the one described in my post was indeed a Maxxforce DT. I get the feeling that the earliest trucks badged and tagged as Maxxforce DT's actually had the earlier DT EGR engines, or maybe some kind of hybrid of the two. At any rate, I have seen some variations in the earlier versions.
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