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bobzilla7

Slow cranking on 4.2 V8

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Can anybody help please - it's driving me nuts! The engine on my Tomcat cranks over real slow - sometimes catches and starts, sometimes doesn't. Once warmed up a bit, there's no problem starting at all. I think the problem has been building gradually.

Sooo, things I've tried to no avail:

Charged battery

Tried another battery.

Checked and cleaned up earth cable.

Checked and cleaned up live cable.

Replaced starter.

Connected jump leads direct from battery to starter and from battery to earth.

Could the timing be out and cause slow cranking? If so, wouldn't I still get slow cranking when the engine is warm?

I then took out the two front plugs out (one on the front of each side) and the engine turned over ok. I next plan to take out all the plugs and see if I can turn the engine over by hand. My thoughts are if the engine turns by hand, then the problem's not in the engine. If it doesn't turn by hand, could it be a broken rocker arm?

Any thoughts much appreciated.

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I suspect the starter motor is past its best ............... then they draw loads of current and run slower.........

Change it for a known good unit.................. (not Prestolite)

Ian

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I suspect the starter motor is past its best ............... then they draw loads of current and run slower.........

Change it for a known good unit.................. (not Prestolite)

Ian

Replaced already with a brand new one from Land Rover. Also tried a spare before that as well.

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Replaced already with a brand new one from Land Rover. Also tried a spare before that as well.

The engine would missfire with a broken rocker.....................

By taking out a couple of plugs you are reducing the load........................

What is the static timing at the moment .................if it is a timing issue then yes, it would happen on both cold and hot, however, you would need a lot of static advance for it to be an issue..........

:)

Ian

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I'm not sure. Had her tuned up professionally earlier this year and she's been running fine up to a few weeks back. I've checked the distributor to see if it's come loose in order to cause a timing issue, and it's not. I'm not sure what the timing is currently set at as I haven't checked. Anyway, if you say I'd have the same problem when the engine's warm, then it can't be that.

There's no misfire and I can detect no loss of power.

Could anything else break in the engine and not cause a misfire?

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Another thought. Does the starter require an earth lead from one of the mounting bolts to the chassis?

There wasn't one there when I changed the starter over, but I have a feeling that some Rangies and Defenders do.

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There should be a thick lead going from the chassis/negative battery terminal to the engine somewhere, just no necessarily to the starter motor bolts.

If there isn't.... or to test if it is the issue (damaged, frayed cable etc.), try a jump lead between the negative battery terminal and the starter motor bolts, if there's a missing/faulty earth then this should bypass it.

You can also check your positive lead in the same way, just dont let it touch anything except the terminal on the starter! ;)

If you do need to replace the earth, it is a good idea to go straight to the starter motor bolts, rather than anywhere else on the engine.

HTH.

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I haven't got any earth lead from the battery to the engine, just battery to chassis. There's also one from the engine to the chassis, tho probably could do with being a bit beefier. The battery is in the back of the truck. I've tried bypassing the + & - leads with jumps leads (very carefully of course!), but haven't tried the neg lead direct to the starter motor bolt. Will give it a go this eve.

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There should be a thick lead going from the chassis/negative battery terminal to the engine somewhere, just no necessarily to the starter motor bolts.

If there isn't.... or to test if it is the issue (damaged, frayed cable etc.), try a jump lead between the negative battery terminal and the starter motor bolts, if there's a missing/faulty earth then this should bypass it.

You can also check your positive lead in the same way, just dont let it touch anything except the terminal on the starter! ;)

If you do need to replace the earth, it is a good idea to go straight to the starter motor bolts, rather than anywhere else on the engine.

HTH.

Yeaaaa! I connected a jump leads from (-) terminal on the battery, to the starter motor battery, then another from the (-) to the engine, and perfect starting cranking first time - BRILLIANT! So thanks for that chaps. Sometimes you do need second opinions! I reckon the old engine to earth lead wasn't earthing out properly. I'll order in some decent leads and for good measure will connect both to the engine & starter bolt to the (-) terminal.

Cheers!

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Good news, mines a real ale :P

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I'm having the same problem with my Rover, and checking the wiring on my starter seems like a good, cheap solution. But how do I get to it? I crawled under there this morning and could barely see the starter beneath its heat shield. And I couldn't figure out how to remove the heat shield either. There's not a lot of space for my hand in there...

Any tips?

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