Hello all,

So just bought an old '76 Hilux and it starts but runs rough. Previous owners cut some of the smog lines and even JB welded over what I think is another portion of the smog system.

I ran a compression test on all 4 cylinders and here are the results:

#1 - 162
#2 - 172
#3 - 180
#4 - 159

Does anyone have thoughts or direction they can give with regard to these results and the hack job on the smog system?

Thanks!

 

looks like #1 and #4 cyl are low. should all be around 170-180. maybe bad valves? bad HG? or bad rings. try squirt some WD40 into the cyl and see if the comp improves. if it does = bad rings. if it does NOT, then u might wanna try a "cylinder leak down" test.

... or try run the vehicle, have the radiator cap open. see if the coolant is bubbling. if yes = bad HG. if no, then most likely the problem is internal.

 

Thanks for the reply. I will try the compression test wet with some WD and hope that its just bad valves or a head gasket......don't wanna deal with rings!

 

Do you require smog? I would compare to engine smog and vacuum diagrams to see exactly what was changed. Either finish the job if it's incomplete or replace what you can. I'm sure JB weld will work as long as it doesn't crack and let air through. The PO of my truck used threaded brass plugs and LCE block plates to seal the ports he removed smog stuff on.

Personally I'd make sure you don't have vacuum leaks and all that jazz before doing leak down tests. I've seen some 22r series Toyotas with cylinders down in 150-160 range and they were still able to run well.