Are all blocks the same?

[asmcnally]

Well, I'm new to the VH45. I am picknig up a car with a VH45 in it, which is has some obnoxious rod knock. I'm well aware of some of the issues with the motor, primarily the chain guides. The motor is currently from a 93 Q45, and since I'm probably gonna pull a junk yard motor I was wondering if there would be any issues with the conversion if I used a 94+ in order to get away from the plastic guides. I don't see there being an issue, but I wanted to make sure that there wouldnt be. I've been trying to find out, but all of my resources seem to indicate it is not going to be a clean swap to get into a 94+.

If I can't get into the new motors, I'd be tempted to just replace the guides themselves and do an inspection of the chain and seals to ensure nothing else needs to be replaced. Is it possible to replace only the guides? Anyone have any "dont do that" for that method?

Thanks

[OwnerCS]

IMHO, replacing the guides is not a bad job.. Many members here have successfully replaced their chain guides. From my experience, here's my personal rating for some service operations with #1 being the biggest PITA (LOL) -- of course outside temperature always plays a major factor in the misery index when you don't have a climate controlled garage:

1) Changing the alternator
2) Under plenum hoses/fuel injectors
3) Timing chain guides (includes water pump)
4) Water Pump
5) Window Regulator removal (clean, lube, or replace)
6) Power Steering Pump
7) Replace belts
8) Oil filter change (under car)
9) Radio Change
10) Climate Control Unit Change

[asmcnally]

Well, I'm really concerned about the difficulty of anything. It's more of when I swap the motors (since the motor is going to be out of the vehicle) what I can get away with to save some money. If I am going to pull a motor from a yard and can get a 94+, which would have the stronger guides I should do that rather than getting a 90-93 and worry about the plastic guides failing me one day.

The current motor (out of a 93 Q45) has some rod knock bad enough that I don't think I can get away with replacing the oil pump and bearings, odds are the crank is going to have to be cut and the previous owner let the oil pump fail (looks like a bad shim, but I havent taken it apart yet). I don't have the available funds to start a rebuild and doing it right so for now a JY motor will do until I get the time and money to rebuild it myself. So what I need to know is are the blocks essentially the same? I'm mating to a z32 transmission currently, and I don't think that would present any issues. But what about mounts and lines? elec connections? Are they all swappable? Exhaust manifolds? Etc...

[Q451990]

My understanding is that the blocks are all the same 90-96. The heads and connectors change in 94.

Heath

[asmcnally]

Mhm, how much did they change? That might be more trouble than worth it. If I have to keep my 93 heads, most likely I will need to rebuild as the previous owner killed the oil pressure. More concerned about funds than the work needed. Most likely if sensors changed, then my ECU won't work too well with it.

Is it possible to just change the chain guides, or does everything need to be changed as well?

Btw - thanks for the info, it's a good start to know that there actually is a difference that supports my findings

[RustyBucket]

The engine sensors did not dramatically change over the lifespan of the G50.

The ECU did change in 1994 with the connectors Heath mentioned, as well as the injectors and chain guides. The NICO ECU for the Q45 is based off a 90-93 ECU core and is compatible with 94+ cars (The 94+ ECUs would require further modification to update the ROM than 90-93). The fact that you can run a 90-93 ECU in a 94+ should tell you that the sensors are electrically compatible. As far as I know the modified ROM on the NICO ECU is the same regardless of what year car the ECU will go into.

The one year I would definitely recommend avoiding swapping into a 90-93 Q45 would be the engine from a 1996. They removed the variable valve timing in '96 and changed connectors again to work with OBDII.

Heath, what did they change with the heads in 1994?

[OwnerCS]

I'm sure Heath has more details about the subtle differences, here's a picture of a 91 model.

1) RTV (Permatex) was replaced with a valve cover gasket.

2) I haven't seen the access panel (between the black plastic coil cover and exhaust manifold) on a 94-96.

3) There was an upgrade to the spark ignitor. I believe the 94-96 has an improved ignitor.