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Author Topic: Low compression, hard cold starts  (Read 2735 times)

March 07, 2014, 01:29:37 pm

Luckypabst

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Low compression, hard cold starts
« on: March 07, 2014, 01:29:37 pm »
I finally have had enough of bump starting my Caddy in the snow. This is obviously a bigger problem than cranking speed, so I broke down and looked a little deeper.

This is what I found for compression, from pulley to flywheel, first dry, then with oil. Engine up to temp.
360, 390
250, 300
350, 350
350, 360

I'm set to re-ring this weekend but I was expecting a much larger change with oil. The fact that the truck would start almost immediately under all conditions before swapping the OEM head with a Topline makes me suspicious of the head. Lousy valve job? Bad lifters? Bad cam timing?

Any thoughts?
Chris



'82 TD Westy
'81 NA Caddy

Reply #1March 07, 2014, 01:44:11 pm

burn_your_money

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Re: Low compression, hard cold starts
« Reply #1 on: March 07, 2014, 01:44:11 pm »
Lousy valve job? Bad lifters? Bad cam timing?

These are my thoughts.
Tyler

Reply #2March 07, 2014, 02:46:40 pm

Dakotakid

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Re: Low compression, hard cold starts
« Reply #2 on: March 07, 2014, 02:46:40 pm »
Does this Argentine head use the same cam bearing specs (can a guy swap)?
But, to do that, one would need overall valve length, and lifter info as well.

Topline sells replacement valves for our OEM stuff don't they? All the specs in that head might be parellel.

Please report any info back as things develop.
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Reply #3March 08, 2014, 01:27:36 am

damac

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Re: Low compression, hard cold starts
« Reply #3 on: March 08, 2014, 01:27:36 am »
Could be totally unrelated but was curious how long is the relay on trucks supposed to charge the glowplugs for?

I had a running engine in a jetta and cleaned it up when taking it out, but just external stuff and deciced to yank the glowplugs and test all of mine on the shelf, etc.

I got an 82 truck and it seems my relay wants to power for 6-7 seconds.

I pimped my glowplug system and just recently started driving this truck since this engine swap.

To my horror the truck did not want to start after one cycle of the plugs.  But if I turn the key off/on real quick and let it cycle again it starts right up.

Very wierd experience, resistance checks out on plugs and I could have sworn I tested each on a battery and made a good pile before installing on engine.

Makes me wonder if I'm getting power to circuit the correct amount of time, or if I somehow mixed some older engines slow or fast glowplugs.

Just thinking out loud because I was surprised to see it took a good 30 seconds of cranking in the cold to even get the car to sputter to start with my tdi starter which is fast, and was scared it was going to run the battery down more than once last week.
1985 turbo diesel jetta

Reply #4March 08, 2014, 05:48:01 am

745 turbogreasel

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Re: Low compression, hard cold starts
« Reply #4 on: March 08, 2014, 05:48:01 am »
Slow (blunt tip) glow plugs take about 30 seconds.
Fast (tapered tip) plugs only take 10 or 12
You are supposed to use the matched type relay.

Reply #5March 08, 2014, 09:00:14 am

RobertMcC

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Re: Low compression, hard cold starts
« Reply #5 on: March 08, 2014, 09:00:14 am »
I would have to bring in possiably leaky head gasket or warped head? you really only got 1 cylinder #2 way off then the rest. Almost 90 PSI difference when shouldn't be more then 25-50.

Should be around 450-500 Plus or Minus 25-50 PSI difference between. Add 20 PSI for turbo. Because its compresses air and inducts it into the combustion chamber. So add 20 PSI ontop of those readings.

Bad timing  1 of 4 cylinder would be in its own stage. One will be in intake, another compression, another power and another exhaust. One would get different readings between cylinders on bad timing.

Did you try the soapy water around the injectors and glowplugs checking for air escape?
2001 Jetta TDI ( 216, CX racing FMIC )

 

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