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Old February 15th, 2018, 04:24   #16
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Quote:
Originally Posted by Mongler98 View Post
how on earth would any debris in an intake port, effect a compression test?
yea i get it, if it was so clogged that not even enough air can get into the chamber or something but if that was the case, i dont think this car would be running
but compression has nothing to do with anything past the valves.
Physics. I've seen it. I've seen intakes so gunked up back in the time before ULSD that the engines quit running.

Only such muck time to pull air into the cylinder. If the port is 50% blocked with crud....

This is why compression checks are supposed to be done with the throttle (where applicable) held wide open.
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Old February 15th, 2018, 04:41   #17
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Physics. I've seen it. I've seen intakes so gunked up back in the time before ULSD that the engines quit running.
Only such muck time to pull air into the cylinder. If the port is 50% blocked with crud....
This is why compression checks are supposed to be done with the throttle (where applicable) held wide open.

Except this isn't applicable on the TDI since it's drive-by-wire, eh?
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Old February 15th, 2018, 04:46   #18
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Correct, the anti-shudder valve will be wide open during cranking anyway.
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Old February 15th, 2018, 05:30   #19
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Pull valve cover, check lifters
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Old February 15th, 2018, 05:42   #20
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Well there is white smoke, coolant was down, and compression is lower in one cylinder. That tells me it could be a head gasket. A dirty intake could prevent a valve from fully closing though.

I wouldn't run it long with out fixing it. I don't know if it could happen with a diesel engine but years ago I had a leaking head gasket on a Rover 2000 TC and it ate the aluminum out of the head to the point of rendering it useless. Lucky for me I bought a wreck in town for a hundred dollars that had the spare parts.
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Old February 15th, 2018, 08:14   #21
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Interesting idea about the EGR. I don't have the plumbing diagram in front of me, could it make sense that a gasket on that system is blown allowing coolant to enter the exhaust while also reducing forward pressure to the turbo causing a loss of power? I think an EGR delete is in order anyways.

Going forward assuming the above doesn't address what I'm seeing, step 1 I'll pull the intake. Based on what I saw with the donor ALH that is going in my 4Runner the amount of crap that gets built up inside the intake of these engines is unreal. EGR + diesel = beyond stupid

Step 2 (and I'll probably do this anyways) pull the intake and clean.

Step 3 Leak down test. Can anyone point me to a kit they used, or just an adapter that hooks onto a quick connect air fitting?

It'll be a few days before I get back at this. I'll be sure to report my findings. Thanks!
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Old February 15th, 2018, 08:28   #22
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If you operate these engines correctly then EGR + diesel is pretty close to a non-issue.

I've cleaned two intakes (and the head on one) and I have zero doubts that I'll every have to clean them again: I won't have to! Tune with Dynamic EGR, proper driving, good oils etc. etc.. And should emissions checks rear back up here I should be good (I can always switch my tunes if needed).
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Old February 15th, 2018, 08:36   #23
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Quote:
Originally Posted by KBCB View Post
Interesting idea about the EGR. I don't have the plumbing diagram in front of me, could it make sense that a gasket on that system is blown allowing coolant to enter the exhaust while also reducing forward pressure to the turbo causing a loss of power? I think an EGR delete is in order anyways.

Going forward assuming the above doesn't address what I'm seeing, step 1 I'll pull the intake. Based on what I saw with the donor ALH that is going in my 4Runner the amount of crap that gets built up inside the intake of these engines is unreal. EGR + diesel = beyond stupid

Step 2 (and I'll probably do this anyways) pull the intake and clean.

Step 3 Leak down test. Can anyone point me to a kit they used, or just an adapter that hooks onto a quick connect air fitting?

It'll be a few days before I get back at this. I'll be sure to report my findings. Thanks!
If the coolant is leaking through the EGR system, that doesn't explain the low compression in the one cylinder. Did you perform the test a few times to average the readings per cylinder?
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Old February 15th, 2018, 09:30   #24
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Maybe the better question... is the Compression tester also Harbor Freight?

In theory, it "should" be off by the same amount on each cylinder... but how much can you really rely on it?
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Old February 15th, 2018, 09:38   #25
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Quote:
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Maybe the better question... is the Compression tester also Harbor Freight?

In theory, it "should" be off by the same amount on each cylinder... but how much can you really rely on it?
I've never heard of one being inconsistent. Only problems have been that they report evenly high or low OR outright not working (usually a bad Schrader valve).

Bigger problem is with technique. Need to ensure battery is properly charged: if the charge drops significantly then subsequent cylinder will read lower due to this. Never thought (or read) about ensuring that the ASV is fully open, as Brian notes, but if he says this is something to check/watch out for then that's good enough for me: another point that lumps in with the need to ensure proper testing technique.
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Old February 15th, 2018, 10:42   #26
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sounds like a bad ring... blow-by.
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Old February 15th, 2018, 10:44   #27
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Yes the compression tester is HF. No I don't expect it to be 100% accurate, only consistent.

I only did one round with the compression tester. I will go ahead and run it a couple more times.

Testing procedure:

Verified battery was at ~12.5V with the ignition off.
Disconnected the IP
Pulled #1 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #1 GP.
Pulled #2 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #2 GP.
Pulled #3 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #3 GP.
Pulled #4 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #4 GP.

Since I started with the #1 cyl the battery voltage shouldn't be the cause of the low reading. And the two tested last were reading even. However, This was the first time I had used this tester so it is possible that it needed to cycle a few times before it will read consistently. Again I will rerun all cyl a couple times and see what they look like.

For those that are asking it's the white smoke and low coolant more than anything that leads me to believe that it's a headgasket. There may be other issues with the engine, that is showing up with the low compression, but by the time an engine is blowing white smoke it's screaming for attention.
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Last edited by KBCB; February 15th, 2018 at 10:48.
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Old February 15th, 2018, 11:03   #28
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While I have never seen an ALH EGR cooler fail, I suppose it is possible. Seen some BHW ones do that.

With ALL the glow plugs out, you can also pressure test the cooling system, and see if anything happens. I'd probably take the EGR valve loose to see if the cooler is indeed bad, you can possibly look down inside it and see pink.

There is a distinct difference between coolant smoke and diesel/oil smoke. One smells sweet, one does not. Coolant smoke looks like steam, diesel/oil smoke will have a bluish tinge to it.

Head gaskets rarely fail on the ALH.
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Old February 15th, 2018, 14:21   #29
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Quote:
Originally Posted by KBCB View Post
Yes the compression tester is HF. No I don't expect it to be 100% accurate, only consistent.

I only did one round with the compression tester. I will go ahead and run it a couple more times.

Testing procedure:

Verified battery was at ~12.5V with the ignition off.
Disconnected the IP
Pulled #1 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #1 GP.
Pulled #2 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #2 GP.
Pulled #3 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #3 GP.
Pulled #4 GP, installed tester fitting, had the wife crank until pressure quit building. Replaced #4 GP.

Since I started with the #1 cyl the battery voltage shouldn't be the cause of the low reading. And the two tested last were reading even. However, This was the first time I had used this tester so it is possible that it needed to cycle a few times before it will read consistently. Again I will rerun all cyl a couple times and see what they look like.

For those that are asking it's the white smoke and low coolant more than anything that leads me to believe that it's a headgasket. There may be other issues with the engine, that is showing up with the low compression, but by the time an engine is blowing white smoke it's screaming for attention.
Look under the car for telltales of dried pink coolant. You could be losing coolant through weeping flanges. Is the white smoke showing even with the engine warmed up? Is it constant out the tailpipe?
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Old February 17th, 2018, 21:19   #30
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I recently went through this exercise: (ended up being a blown head gasket - but there are different blowout scenarios that behave differently - and I did not have a compression-tester).

My ALH never had white smoke coming out of the exhaust. It actually pretty much ran fine, and for several months, would take 10-15 mile drives on a daily basis, but if you drove it on the freeway, it would overheat. This was apparently triggered by a low-coolant episode caused by a leak in the radiator return hose. (or, possibly, after the leak was repaired, the car was driven with too-dilute coolant, because the lost coolant was replaced with distilled water; which makes it boil at a lower temperature, and also degrades the viton in the MLS head gasket).

Coolant leaks can be traced (even EGR leaks) with a fluorescent tracer dye. If it is ingested in the EGR valve, you should see trace in the intake downstream from the EGR with a UV light. If there are leaks anywhere else: fluorescent tracer dye will reveal it. (unless it's coming in through the water-jacket and head-gasket; I don't think there's a practical way to look in there if there's even trace visible). Though, when I took my EGR cooler off, I looked at it, and couldn't really imagine how that could develop a leak, it's a pretty sturdy and solid piece of hardware. (and very, expensive to replace). I used my mighty-vac, and rigged a sprinkler fitting, and just plugged the other end with my finger; and it held vacuum, so I figured that meant it was airtight.

If you see bubbles in your coolant reservoir coming from the coolant return hose, or soot, or if the coolant system is pressurized after sitting overnight, or if the pressure relief valve in the expansion tank getting tripped and level going up, any of those mean that you've got a blown head gasket. If your expansion tank is overflowing, then you'll see coolant on the ground under the car behind the front-right tire just generally dripping from the frame. (for me, it was actually kind of hard to figure out where this was coming from until I got the dye - but in retrospect, looking at the expansion tank being filled; it was obvious).

White-smoke has already been covered; so here's the thing about whether the white smoke is fuel, or coolant:
If it is fuel, this could be the result of a blocked intake, and you can rule out two pretty common causes.
That could either be build-up of soot in the intake, (which has also been covered), OR, a broken EGR cut-off butterfly; the little plastic vacuum actuator on the back of the EGR is pretty fragile, and commonly breaks, and if the arm is broken, then the butterfly valve can kind of flop loose. You'd see that immediately if you took off the intake hose. If it's closed, you'd get really crappy power, and white smoke that smells terrible. There is a lever on the back of the EGR assembly that you can control with your finger (if that plastic arm is broken, or disconnected).

So that's easy to rule-out. I thought I'd mention it. And unburnt diesel is really stinky.
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