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1982 and 1976 300d differences

Still have (and working on) my 1976 300d. Just acquired 1982 300td. WOW!! Big difference in starting engine between the two. 1982 just starts with a turn of the key once the glow plug lite goes out. 1976 has to be cranked over a few times. Run about the same amount of petro and biodiesel in both. 1982 has 223k miles, 1976 shows 80k, but more likely 180k miles or 280k miles (most likely). Replaced both fuel filters, as well as oil and air on 1976. Replaced valve cover gasket on 1976. Checked valve clearances while cover was off, all clearances are at least the .10mm and .30mm as indicated on cold check.

Now the questions:

  1. Would getting the valve clearances EXACT help the 1976 start quicker? (most clearances are more than spec).

  1. Why does the 1982 start SOOO much easier than the 1976?

  2. Should the 1976 have to be cranked so much to start?

  1. What can be done to 1976 to make it "less cranky"?

Note to TG - great info you gave me - very informative and helpful.

Thanks in advance! Bob

Reply to
biodieselbob
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Not sure what exactly you mean by most clearances are more than spec, as that could mean they are off by a hair or by a mile. Also, if you had the valve cover off to check them, why not adjust then at the same time? Valve clearance is a factor in starting, but unless they are off by quite a bit, I would expect it to only make a signifcant difference in starting at colder, winter temps.

Because something is wrong with the 76.

No

My first suspicion would be the glow plugs. Next, compression.

Reply to
trader4

You're welcome.

Loose valves will actually be better for starting an engine vs. tight valves which may be so tight to be slightly open and allow compression to escape.

The newer car has pin type of glow plugs which heat much faster than the older style. As a test, glow the old car three times before cranking it

- that will cancel any differences between the two glow plug types. Then if the older motor still needs to crank a bit - and give it a bit of accelerator (gas) - then a compression test is needed to confirm that its compression isn't all that it should be.

Reply to
-->> T.G. Lambach

First thing I would do on the 76... check each glow plug resistance... you have to disconnect each one to measure it accurately. They should all be less than 1 ohm resistance.

If you find two bad, then you might as well upgrade to the pencil type glow plug... this also means new relay too. They sell kit so it is easy upgrade.

Another check is fuel system... are you getting air bubbles in the fuel filter? You must eliminate any air bubble... so that means changing out the fuel hoses.

Reply to
Tiger

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