Replacement engine

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littlepolo
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Re: Replacement engine

Post by littlepolo »

While waiting for the vacuum gauge I could not resist having a look over the engine again. I removed the throttle body to check the seals and all looks OK. I mentioned the breather hose from the oil separator which seemed to be a bit loose at the top (it would move laterally and was easy to rotate), so I took this off to have a closer look at the O ring. When I unclipped the pipe and let go the whole pipe dropped to the floor. It had come adrift from the oil separator. On inspection both O rings are flattened from wear and should have been replaced.

One other symptom I found yesterday when running up the engine was a slight hesitation/lag on the throttle when warm. after thinking about this last night that made me pursue a vacuum leak. I've seen some hoses that are simply the rubber push on type (specified for my vehicle) - which type is best? Should I replace the O rings on the corrugated hose or get a new rubber hose?
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alexperkins
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Re: Replacement engine

Post by alexperkins »

I would replace the orings (they need to be viton else theyll soften - whats fitted should be light green?). The corrugated pipe is typical on this engine, and its better to use that than push on rubber hoses. VW use this from now on.

Can you pop some pics up of your findings?
littlepolo
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Re: Replacement engine

Post by littlepolo »

The hose was swapped from the donor engine because when I stripped down the original it kinked/split at the elbow. The O rings fitted do not look like they were light green. It was my mistake not to replace them and I did notice the couplings did not clip on securely. I blame the freezing temps and working outside. I'll use whatever I have to hand for now to prove the point.

I'll pop some pics up later.
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alexperkins
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Re: Replacement engine

Post by alexperkins »

Are we referring to this hose - Image

036 103 493 BM - £22.57
littlepolo
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Re: Replacement engine

Post by littlepolo »

Yes, that is it except it has the plastic annular ring connector at both ends. Replaced the O rings and refitted. It might have fixed a vacuum leak but it has not fixed the running problem. It seemed to run a bit smoother from a cold start and it appears the hesitation is slightly reduced but it will not idle when warm (revs drop off). O2 is correcting with a -50% - 60% at 1800-2500rpm which indicates overfuelling. Difficult to start once it stalls.

I'll wait for the vacuum gauge to arrive.
littlepolo
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Re: Replacement engine

Post by littlepolo »

Vacuum gauge arrived. Disconnected the MAP sensor so I can run the engine a bit longer to test with the gauge. Definitely runs rich like that.

Plugged the gauge into the evap line that runs into the throttle plate and got the engine warmed up a bit.

At idle the gauge was between 7 and 8 inches Hg and the needle was vibrating more or less within that range. This is way below what the MAP sensor was reporting (700mBar at idle which is approx 20 inches Hg). What is the correct interpretation of this reading please?

Edit: At a fast idle (approx 2000 rpm) reading was around 12 inches Hg. A blip on the throttle took the needle down to approx 2 and it bounced up just over 20 before settling back to where it started.
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alexperkins
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Re: Replacement engine

Post by alexperkins »

Idle should be around 17-21 Hg

http://www.gregsengine.com/using-a-vacuum-gauge.html

Altitude dependent of course

Sounds like you have a vacuum issue
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alexperkins
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Re: Replacement engine

Post by alexperkins »

Could it be that your timing is out? Valve timing will screw this up tenfold

Also, intake manifold air leaks can cause this.
littlepolo
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Re: Replacement engine

Post by littlepolo »

I will have to strip down the intake manifold to verify the seals are OK. However, I'm leaning toward a timing issue. Not sure if I can post a URL here but I found an interesting (albeit lengthy) article (by coincidence a Polo) where the timing chain stretched and caused valve timing symptoms with large fuel trims, etc.

The vacuum reading is borderline vacuum leak and valve timing (the latter usually 8-14 inches Hg). The vibrating needle could be valve overlap.
Thinking about it, a valve overlap would dump fuel into the exhaust stream and confuse the O2 sensor.
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alexperkins
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Re: Replacement engine

Post by alexperkins »

You can post a URL here - just paste it in.

The BBY 1.4 16V doesnt suffer from timing chain issues - its belt driven. The 1.2s however have endless timing chain issues.

Yes it would, i think your cam timing is out
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alexperkins
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Re: Replacement engine

Post by alexperkins »

Image

You installed the crankshaft outer pulley correctly with its alignment notch i assume?
littlepolo
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Re: Replacement engine

Post by littlepolo »

alexperkins wrote: Fri Jan 05, 2018 3:58 pm You can post a URL here - just paste it in.

The BBY 1.4 16V doesnt suffer from timing chain issues - its belt driven. The 1.2s however have endless timing chain issues.

Yes it would, i think your cam timing is out
Thanks. I know it's not chain driven but there are similarities with the symptoms. However, my fuel trims are much higher (negative) and I have no fault codes which I find surprising considering the massive fuel trim adjustments.

https://www.picoauto.com/library/case-s ... ault-codes
littlepolo
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Re: Replacement engine

Post by littlepolo »

alexperkins wrote: Fri Jan 05, 2018 4:00 pm
You installed the crankshaft outer pulley correctly with its alignment notch i assume?
Missed your comment.

I used the crank sprocket (timing belt drive) to align the timing - sprocket beveled edge against the casting web. The aux drive belt pulley was then fitted over the locating key.
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alexperkins
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Re: Replacement engine

Post by alexperkins »

I can see the similarity. I think your cam timing is out reading up on that link, and with what we are seeing

check the timing with the screenshot i posted from Elsa and post your findings :) We'll get this fixed
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Re: Replacement engine

Post by littlepolo »

How many hours labour would it take a decent mechanic (not myself) to verify and/or correct the timing?

Think I need to have it over to the experts (also running out of time).
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