Jump to content
SAU Community

Recommended Posts

Hey guys trying to get a silvertop motor going here and have a very annoying prob.

I got the motor off someone and it had no compression. So I get it home and rip the head off expecting to see scored bores the rings lands melted etc. Upon inspection and taking the bottom end apart it was completely fine.

So then I check the head out, turn both the inlet and exhaust over and all the valves etc are moving fine.

So I put it back together but when cranking it over it the starter motor does not strain what so ever like there is no compression.

So I thought the timing may have been out but its all good, cams on TDC and bottom end on TDC too.

But still just turns over way too easy, I am suspect on either the inlet or exhaust no completely sealing off which may cause it.

About to go out and get a comp tester, but I am 90% sure it will show nothing.

Any suggestion what could cause this?

I have no exhaust many on, but that shouldnt matter.

Link to comment
https://www.sau.com.au/forums/topic/131873-rb20-issue-suggestions-welcome/
Share on other sites

Are the spark plugs in the motor? Also piston rings could look ok, but not seal the combustion chamber. The valves may move ok, but are the seats ok? And if you took the motor apart and re-assembled it with the same head gasket, any chances of making compression are greatly reduced.

Are the spark plugs in the motor? Also piston rings could look ok, but not seal the combustion chamber. The valves may move ok, but are the seats ok? And if you took the motor apart and re-assembled it with the same head gasket, any chances of making compression are greatly reduced.

Spark plugs in yeah, rings are ok as I took the head off and put it onto a known good bottom end.

Brand new head gasket too. I suspect on the seats for now, taking the head off now to check it out again.

Tested with a comp gauge and it registered 0 accross all 6. Its torqued down to spec too.

stupid question, but you said the starter felt like it wasn't using much effort to turn the engine over... i take it you're doing the compression test by kicking the engine over using the starter with the coilpacks off?

have you checked that the starter is actually engaging and turning the engine over? I.e. are the belts at the front of the engine turning when you kick it over?

like i said, sounds simple, something worth double-checking though...

yeah found out what it was, the valves were bent.

At first glance it appears to be fine but when looking under each valve from the side they are slightly bent.

I suspect it was over reved, going to need new valves.

Edited by James_03

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Didnt realise RB's had more then 1 head.
    • I'm normally copping my own abuse from neglecting my daily drivers. "Those suspension bushes will last a bit more", "Don't worry about the oil leak, just keep topping it up". The project cars I'm always doing things slowly on them as I'm wanting them to be done better, and neater, and nicer. Luckily I don't have to deal with 18 year old Matt's "Learning to wire" stuff in the project cars. And there's only one piece of wiring I'm displeased about in the Landcruiser, and it's about to be cut out... However, the box loads of parts that have been going through this place lately for the Landcruiser... Brake pads Brake Rotors Full handbrake overhaul Wheel Bearings Seals Swivel hubs Steering Boxes Half the suspension joints Shocks Air bags (Ones to go in the rear springs for towing) Water pump Timing kit Lower timing case Harmonic Balancer Radiator Lots of other little seals and shits Gas struts for the bonnet New power window switches And god knows what else I've forgotten... Ha ha ha I have my fingers crossed the pinion seals don't start leaking on the diffs, that the transfer case doesn't leak, and the gearbox input shaft doesn't leak, nor the rear main seal. As they're about the only seals I haven't replaced in the driveline! I'm seriously eyeing off buying new caliper rebuild kits front and rear brake calipers... I'll probably recheck all the valve clearances soon too, and hopefully, it should be all good and sweet to haul some long distance trips again!
    • Every time I pull my 3x gauges out of the console and see the crack-addict way that I did the wiring, and I just can't bring myself to tear it all apart and "make it nice", because it is currently working. In fact, the last time I was in there I probably made it worse.
    • The best part is when you own the car long enough that you look back and find your OWN ham fisted amateur shit!
    • The annoying part about neglect, is when you start to replace one thing, and find ten more broken things. Ham fisted monkey repairs you normally only find out about when trying to do something unrelated! Ha ha   Neglect you can kind of anticipate the huge costs to fix it all. Ham fistedness is normally a shock the first time your work on a new old car, as everything "looked" good before.
×
×
  • Create New...