R51 (YS 25) engine rattle when cold and driving

[ShmoeMo]

Hey guys,

My pathy has an engine rattle (kinda sounds like skirt slap but more diesel knocky) at about 1700 rpm to 2800 when cold but if your on a good amount of boost between this rpm range it does not rattle but does rattle again when you stop making boost and plateau to the throttle level you are inputting. Once i have driven a few KM (2-7 km) and have got a bit of heat into the engine its gone. Could this be injector rattle or just a typical cold diesel thing? (this is my first diesel car) average temp on the way to work at the moment is probs 12c. I will conduct an experiment next time i fuel up, i will go to caltex instead of united and see if there is any difference. and will also be doing a oil change in the next few weeks.

 

[Old.Tony]

There could be a few things at play here. Some of them are cause for concern.

If yours is a YD25 (4cyl 2.5L diesel) from between 2007 and 2011, the timing chain could need attention. Specifically not the chain, but the chain tensioner (which causes the chain to stretch and start destroying bits and itself). This is often caused by sludge locking the tensioner in place, making it difficult to move and keep the chain tensioned, and is loosed through heat and starts working normally again. You could try an engine flush but if it's bad, you really want to manually clean it up and see if the tensioners need replacing. Using a mechanic's stethoscope on the timing chain housing when the engine is cold will tell you if it's the chains.

There's also a chance that it's exhaust gas sneaking out of the system. In mine, the gasket between the exhaust manifold and turbocharger began to thin out and started to act like a reed in a clarinet, so that at certain engine speeds it would sound like the worst-played clarinet in the world. Look around all the joins for black sooty deposits, and check the EGR tube (the gold tube that goes around the front of the YD25 engine).

That's a start, anyway. Check the heat shields for loose bolts and stuff too, while you're poking around in that area, particularly off the dump pipe.

 

[ShmoeMo]

Na it's defs not timing chain. Have heard that before. Exhaust gaskets are OK. It's not a light clicking / claking or Reed noise but more of a diesel knock mixed with skirt slap. I'm thinking injector rattle as it sounds exactly like this video except for me it goes away under boost and comes back when coming off boost. Skip to 1:30 to hear it.

 

[Old.Tony]

Have you run any injector cleaner through to see if that helps? Liqui Moly have a product called "Diesel Purge" that requires you to take fuel hoses off the filter and use in the can, which really rips the crap off the injectors.

Failing that, it might be time to pop the injectors and give them a good looking over. I'd try the cleaner first. obviously - it can never hurt the engine, and might fix it. That Liqui Moly stuff is pretty good.

 

[ShmoeMo]

No I haven't tried any cleaners yet. I was going to wait till I need to fill up again and try a different company's fuel. Using united atm coz I get it cheaper with my ract gold (aussie version of AAA) will try caltex diesel next time. If that doesn't help I will have a look at that liquid moly stuff

 

[Old.Tony]

Caltex "Vortex" diesel is supposed to have detergents in it to keep your engine cleaner. I've no evidence apart from a sticker on a Caltex pump that announces it.

 

[Billy54]

There is also a product called 'Fuel Doctor' that you just add to your tank when filling up. Great for diesel fuel engines. Use it on a couple of fills and you will notice a difference. Old Tony is right in saying start with the easy solution first and the fuel additive can't hurt.