Oil Pressure Issues 3.6L LLT Engine
Good Morning Fellow Techs,
Hope everyone had a good weekend. I am posting this due to a concern for a vehicle that is coming from another shop. The Story of the vehicle goes like this. The customer was driving their vehicle and during this process the timing chains jumped timing. The vehicle ran rough but did not bend any valves. The customer decided to have the timing chains replaced. The Shop that replaced them said that after the chains were replaced the oil pressure is now low. They replaced the oil pressure switch. This did nothing for the oil pressure lamp or pressure.
The vehicle now has Sat for 2 years and it has been towed to us. At this point we started by checking the oil pressure. The oil pressure registers only around 20psi on a 20 deg Michigan morning start. This pressure drops off rapidly as the vehicle warms. The engine honestly doesn't sound that bad while running but the oil pressure drops below specs after getting warm and eventually at Idle it the oil pressure light is dinging at telling you to shut off the engine. The oil pressure at this point is nearly 0-5psi. If I rev the engine it goes up again but as soon as we are back at idle the oil pressure is too low once again. I am wondering if there are any common is that any of you have seem that would cause this other that worn internal engine components. The Customer really want to throw an oil pump on it but I am not willing to just jump into it without a little more confidence. I have verified oil level and type of oil used. I tested the oil pressure on the Filter with an adapter as well.
Any thought or experiences would be greatly helpful.
Likely a result of some careless work when the chains were done. I think you’ll need to get to the oil pump and inspect it as well as the pick-up. Then you can decide if it’s getting a motor 😉
You could check the pickup screen for sludge. Otherwise if u want to find the actual issue you will need to teardown an check clearances, oil galleys, etc like any other engine. However these engines are garbage and it may be easier to just quote a new engine or tell customer they may want to think about a new car.
Could be an error when timing was done. Could be pickup. How is compression? Check wet vs dry compression numbers or even doing relative compression. Then make an educated guess from there… you could also pull a valve cover and get a better idea of engine internals that way. If customer wants a pump and they know the possible outcome… Your going to have to access the area behind the covers…
Low oil pressure only has a few causes: either the pump is bad (stuck relief valve), or the engine has clearances that are out of tolerance. Since the chain jumped, it obviously had prior issues before that. Or, the oil pressure dropped and the chains jumped. Either way, this will take some digging to find out what happened. This engine is not as bad as the earlier generation 3.6Ls, but still…
I would pull off valve covers look for blueing at the bearing caps , it may of had a prior undiagnosed issue or run low on oil that led to the chains stretching and jumping cause it’s dragging an unlubricated camshaft along causing the chain to be under a lot of stress . Maybe a maintenance records interview with customer may shed a direction for you to take.
That's a good point, It might be a good place to start just to removed the valve covers and inspect.
There are bolts on the front of oil pump that hold the middle chain guide. I've never messed with them myself. There is a video on youtube by Cloydes that explains that you don't unloosen these bolts. Personally, I won't try to fix this unit. I would sell a replacement unit… to expensive to try to fix. Also had one that when I took out oil filter, it was full of plastic shavings from the…
not familiar with this engine in uk, but sounds like low pressure reason for timing chain failure. agree with earlier comment, oil pump only supplies volume, tolerance in bearings etc create pressure. going to require major surgery or replacement engine. if vehicle stood two years would not be keen getting involved. dont make someone else's problem yours unless customer understands implications…
Yeah I am tending to lean that way as well. I would tend to feel that if this customer is well informed of the implication then I am ok with the repair. It can be really hard to know in situations like this.