Engine knocking

[Mazdax605]

Hey everyone,

Today I noticed my engine in my Delica knocking really badly at times. Not always, but when it does it it sounds really bad. It seem at low rpm, with load it will knock for a few seconds, and then clear up. Also getting heavy smoke when the knocking occurs. Even seems to knock with trans in neutral, and revving the engine, but not as badly, and at a higher rpm it seems. How bad is this, and what should I be looking for. Sounds like marbles in a coffee can bad. Seems I'm not hearing the same whistle I normally hear from the turbo as well. Related I'm guessing?

Van has 91k KM's on it, and is totally stock. 89 Low roof auto if any of that matters which it shouldn't.

[Growlerbearnz]

By "knock" you mean the usual diesel rattle noise, but much, much louder, right?

Since it's intermittent, my first guess would be a failing injector. A diesel or fuel injection shop (there are a few in Boston, and it looks like South Shore Diesel in south Middleborough) should be able to test the injectors and rebuild them if needed. They'll need to be removed from the engine to be tested.

It might also be the injection pump. The advance plunger can stick which causes it to inject at the wrong time, giving the symptoms you're describing, but the injectors are cheaper and easier to check first. If you end up needing a rebuilt injection pump you're going to want rebuilt injectors anyway, so you might as well start there.

[Mazdax605]

If I end up needing an injection pump rebuild /replacement is there a how to online that can step me through removal /reinstall? Also I'm assuming the pump is nothing crazy and is like any other rotary injection pump, meaning it should be rebuildable by any competent diesel shop. Any online specs for the pump?

[Mazdax605]

Also, if the advance plunger is sticky, can it be fixed with any sort of additive in the fuel, or is it only repairable with a teardown? I'm leaning towards the advance plunger because it doesn't act funny at idle, and only makes noise when revving.

[Mazdax605]

Okay so under further investigation and taking the van to south shore diesel I think it may be turbo or EGR related. I drove the van over to the diesel shop and had no issues what so ever. He listened to it, and revved the snot of it with no issues aside from a puff of smoke here and there. When I say he revved the snot out of it, I mean he put it to the floor and revved to almost 5k rpms without any noises, or problems aside from a little smoke here or there. I then drove it home, and had a few issues, but it was very intermittent. Now driving it around more during the day it seems every now and then when taking off from a stop or accelerating from slower speeds it seems like I have no boost, and the engine falls on its face for a few seconds, makes some noise that sounds unpleasant, and then comes around. Any chance the turbo could be going bad? Or possibly a sticking open EGR valve?

[Growlerbearnz]

I don't think a failing turbo would cause the symptoms you're describing. Turbo failure tends to be either very gradual (less boost, more blue smoke, more/scary whistle noise) or very sudden and extremely alarming.

I wonder if your wastegate is sticking open? That wouldn't explain the knocking noise, but it would explain the smoke, lack of power, and lack of turbo whistle.

It *might* be the EGR? Try disconnecting the vacuum hose that goes to the EGR actuator. Plug the hose with a screw or small bolt, and drive it like that for a while.

If the advance plunger is sticking you *might* free it up with some kind of additive, but I wouldn't expect the fix to last. The advance plunger lives at the bottom of the injection pump, so any cruft tends to collect there. The advance plunger cover plate is also a source of fuel leaks, and I've seen one or two that have been sealed with silicone (rather than just replacing the O-ring). The silicone gets into the plunger mechanism and you have to rebuild the injection pump. Look for leaks or sealant on the cover marked "timing device" in this picture:

pump1.jpg (55.64 KiB) Viewed 10182 times

[Mazdax605]

Brought the van to an all Japanese car show on the 16th. About an hour drive that was mostly highway. Performed flawlessly. Won two trophies somehow. Got in the van to leave and had some really black smoke and low on power for maybe 2-3 minutes but then ran fine the rest of the way home. Drove it last night and today with zero issues. No idea what is going on with it.

[Mazdax605]

Hello everyone. I don't post up in here much anymore for whatever reason. I will let you know that on Sunday I changed the oil, and oil filter on the Delica, as well as the fuel filter. I also disconnected the vacuum line to the EGR valve. I took the van out yesterday evening to go play volleyball. It is a 30 minute drive on secondary back roads and such. The engine made no bad noises like it had been doing from time to time even on Saturday when I had it out. So either the fresh oil, fuel filter or EGR fixed it. Well maybe fixed it. I will drive it more to see if the symptoms return, but it was fine in the trip to and from volleyball. Had I not rolled my ankle badly it would have made for a nice evening.

Could a sticky EGR valve cause the engine to fall on its face, and smoke badly, plus make awful noises?

[Morgonzo]

Hey Mazda605, I don't think the oil change would be a factor in the issue you're having. The fuel filter could have been clogged causing irregular fuel flow, and changing it solved the issue OR your 25 y/o EGR is not functioning properly and since you basically shut it off by plugging the Vac hole you solved the problem. I personally removed my EGR after get the van and installed blanking plates (pretty easy to do..) and have had significantly less smoke. If you were to pul your Injectors (again not a hard job..) and had them tested they most likely will come back as needing a rebuild. It's just the nature of 25 y/o finely calibrated machinery.
And like GB said, you could run some Seafoam or 2 stroke through the system either directly from a container into the fuel pump or diluted in the fuel tank and it will clean some junk out and maybe quiet some of the chatter but no additive will rebuild your injectors or fuel pump from the inside.

Congrats on winning those trophy's btw

Cheers.

[Mazdax605]

Thanks for the response. I don't think the oil change did anything either. I hope to remove the injectors and get them tested soon. I want to block off the egr ASAP. Maybe even install an egt gauge.

Chris

[Mazdax605]

So, if it was the EGR that was causing my issues(not convinced), what was it doing that could cause it to run so poorly, and sound like it was coming apart?

[Growlerbearnz]

EGR directs some exhaust gas back into the intake manifold. The exhaust gas reduces cylinder temperatures which cuts down NOX emissions, but it also reduces efficiency and makes diesel ignition unstable.

The EGR valve is only supposed to operate when the engine is warmed up and running at cruise condition (revs between 1800-3000, accelerator halfway or less). At that point the engine's running well enough that the disturbance to ignition isn't noticeable, and the drop in power isn't important.

If your EGR valve is sticking open it will be letting exhaust gas into the intake when the engine is cold, or running too slowly to mask the poor ignition.

I wouldn't have thought it would be *that* noticeable, but I've never tested it. Next time I see an engine with the EGR in place I'll jam it open and see what happens.

Here's a better description of what happens: https://dogandlemon.com/articles/owners ... r-problems

[sk66]

I cleaned/tested/reinstalled my EGR valve, and I also had it removed/blanked for a while... can't say that I noticed any differences. Also note that the EGR is controlled by the glow plug control module... if that's toast your EGR is likely non-functional at best.

[Mazdax605]

So, I think I may try to remove the EGR valve, and see what it looks like on the inside. I think I'd like to blank it off, but right now , maybe just give it an inspection, and clean up. What are the chances I can get it out without ruining the gasket? Where can I get a new gasket for it?

Also it looks like the oil return line on the turbo of my van is dripping a bit. It seems like it shouldn't be too tough to get to, but where can I source a new return line flange gasket?

[sk66]

The EGR gaskets are metal. I was able to reuse them. But they are available on ebay.