1997 Hilux 5L - Zero intake valve clearance
Hey all, I was hoping for some advice. I have a 1997 Hilux LN147R with the
5L engine, naturally aspirated. I've been having problems blowing black
smoke under load. After replacing air filter, my next port of call was installing
fresh injectors. When removing the throttle body housing to get to the
injectors, I noticed it was full of black crap. Anyway, whilst I was in there, I
decided to check my valve clearances (bucket and shim type). My exhaust
valves were a little tight and out of spec, but all of my intake valves are so
tight I can't get my 0.03mm feeler under there! My question is this, could the
tight intake valve, cause it to be slightly open during combustion and gasses
blowing up into the valve cover, through the breather and into the throttle
body? Also, should I pull the shims and get them back into spec or is it likely
i'd need a valve job. What would you guys do in this situation?
Many thanks in advance,
If there's no lash, the valves could be slightly open during combustion, but they'd be slightly open during compression as well. Have you noticed a drastic loss of power in this car? all evidence seems to point to your conclusion and I think your approach to fixing this is correct. I do think that burned valves are a result and will need a grind, I'd do it anyway, and this should be done before proceeding with the other repairs or adjustments.
Thanks Ed92626, I feared that might be the case. So to clarify, you'd pull the head and grind the valves before making any shim adjustments? Would I be a fool to adjust the shims first and wait to polish the valves further down the track? This is my daily driver so I can't have it out of action for too long. I haven't noticed a reduction in power particularly. Also, if you were going to pull the head and grind the valves, would you do a complete valve job and resurface the head whilst you're in there? Sometimes is hard to know when to draw the line..
You can try whatever you want. Who knows; it might work. I don't like to redo things and after you remove heads, you'll have to adjust the valves anyway. If you don't have a compression problem, why would you resurface the heads? Clean mating surfaces and a new head gasket should be fine. I was going to recommend a compression test, but the valve problem will likely prevent that..... If it were me, I'd do all that's potentially necessary and get replacement transportation until the work is done.