'93 vert broken timing belt

[steevano]

I have a 93 vert with a broken timing belt. I know it is a zero tolerance motor so I assumed there are internal issues and picked up a short block from a 90 2+2. Am I correct in the thought that the 90 heads will bolt directly on to my motor? If so any recommendations on what I should have done to the heads before installing and other than bent valves what should I look for when I break my motor down? thanks

[nissanfreak12]

Before you break the motor down, do a leak down test. There is a chance there was no bent valves. It is seriously a 50/50 chance though. Myself and some friends had luck, but just about the same amount of people had bad luck.

Bent valves, damaged pistons, rods(extreme though), rod bearings, crank bearings, crankshaft. These are all issues that can come from interference with breaking a belt. MOst are an extreme issue like it breaking at 6k+ rpms on acceleration, but still good to check. Sometimes you never know.

[steevano]

Will do. It broke as I was slowing to stop 20mph or so but I did crank it over several times so we'll see... thanks

[DCaff300ZX]

IIRC there is an issue with the '90 heads and "soft valves" with "P" marked heads, but unfortunately I can't elaborate further as I have no personal experience there...but it is an important issue. Perhaps search will help there.
Another issue is the 1990-1993 old style injectors and methanol in gas, plus the crappy connectors all over the engine (your '93 vert due to production date has the new style injectors/harness/connectors)...basically, if replacing a Z32 motor you are best off with a 1994 or 1995 version with all of those upgrades plus the new wiring harnesses needed/recommended in either case.

[RubyRed300ZX]

You have the old style injectors and connectors unless a previous owner changed them out. Your 1993 Convertible was a 1992 Slicktop when it left the factory in Japan. When buying parts, you need to refer to it as a 1992.

[DCaff300ZX]

My bad, sorry OP...thought the verts got the new style along with the NA's. Good catch RubyRed!

[steevano]

thanks RubyRed and yes the 93 verts have the older style inj. Trying to get my hands on a leak down testor and hope to get busy on it this week. Is there enough value in this gen of verts that I should try to keep it a numbers matching car, I'm the 2nd owner and it has 120k?

[DCaff300ZX]

I've seen conversation regarding thoughts of value gains for Z32's, and the verts would be among the more desirable due to lower production numbers quite possibly. Helping things I'd assume would be a rarer color code, low miles, and yes, original OEM working parts.
But I wouldn't view it as a possible cash cow to come, just that you would get a maximum return for the car in the future should you sell it rather than the car has lost further value, or stagnated.
My own view is a Z32 is always worth restoring if possible and affordable to the owner, and is also a very personally rewarding venture if your bank account makes it out alive and you are still sane!

[steevano]

make sure Im on the same page as you nissanfreak12, a radiator/cooling sys leakdown?

[nissanfreak12]

Cylinder leakdown. If you do a pressure test in the coolant system, it may not show an actual issue.

I have seen a lot of ways to do it, and they are basically all the same. You can actually make your own gauge. Really not too hard to do. If you install another timing you can do a compression test, buts thats just a lot of work. Even though its not at "operatng temp", it will still give you an idea of what is going on.

https://mobiloil.com/en/article/car-mai ... kdown-test

You can try just using compressed air to push in the cylinder without a gauge, just make sure the cylinder is at TDC and the valves are closed. Listen for the air escaping;

Air coming from intake- Intake valves not closed or bent
Air coming from exhaust-Exhaust valves not closed or bent
Air coming from oil dipstick-bad piston rings/oil control rings(this should be expected due to engine being cold, but shouldn't be a lot of air)

What you are looking for is mainly air from the valves, because bent valves from a belt break. Your head gasket should be good and your compression rings/oil control rings same. Unless you bent or broke a piston or really bent the hell out of valve. You still may get some air from the valves, but if they are good, you should be able to push air in and it doesn't escape at a fast rate through the valves. If you put say 50psi in the chamber and stop you should still hear air escaping somewhat evenly. If one escapes a lot faster than the other, there is an issue.

[steevano]

Thank You! This makes complete sense, granted its not perfect but should give a clearer picture of what I'm looking at...

[DCaff300ZX]

Agreed, excellent solution nissanfreak! I like the way you think. I wish I'd have thought of this when my own past boost testing caused concerns from hearing the air escaping the open valves, this solution isolates each cylinder results and keeps things clearer- nice!

[steevano]

When I do put this on the road again (now that I have a spare block and heads I'm covered regardless the outcome) in the near future, do you have a recommendation for upgrading the brakes? As it is now, I can easily outdrive the stock system and will be swapping to coil overs which will make a bad situation worse... I have no problem throwing cars around on gravel/dirt without using brakes (30 years playing in Rally Cars) but never found that advisable on the street...

DCaff, r u familliar with the "Russian" down in Portlandia?

[DCaff300ZX]

The "Russian"?
Nope, new to me...although I do know that there is a pretty big Z contingent down that Oregon way, and now that I think of it, are you talking about Roman Tenyanin (may be mis-spelled...) of BBT performance in Vancouver, Wa.?

[steevano]

The Same...