Q45 engine serial no.

[PaulR]

I have a 94 Q45 with 80K miles.

I bought the car from a relative. He bought it in in 95 and kept it garaged and didn't do many miles.

In the early 2000, after a screwed up oil change, it lost oil pressure, which damaged the engine. The service shop replaced that engine at their cost with one that they said had lower miles. I believe that it was a low mile engine because even now, it's still clean, with only slight seepage from the rear main. But, not knowing the actual year it was made, I'm trying to find out when it was made because of the change over from the plastic to metal timing chain tensioner.

I used a boroscope to read the engine serial number on the back of the block. It wasn't easy to find, and because it appears to be cast into the block, I question if it is the serial number. In any case, does anyone know how to read the number to determine the year of manufacture?

Thanks for any help.

[VStar650CL]

The last time I tried to track an engine serial number, I was told by DPiC that the only records of that are kept by the factory. The internet says the Q45's were all built at the Kaminokawa plant in Tochigi. That plant is still in operation, 2500 Kamikamou, Kaminokawa, Kawachi District, Tochigi 329-0692, +81 285-56-1204. You could contact them and see if they'll help you out.

[PaulR]

The last time I tried to track an engine serial number, I was told by DPiC that the only records of that are kept by the factory. The internet says the Q45's were all built at the Kaminokawa plant in Tochigi. That plant is still in operation, 2500 Kamikamou, Kaminokawa, Kawachi District, Tochigi 329-0692, +81 285-56-1204. You could contact them and see if they'll help you out.

Thank you for that info.

I'll look into contacting Infiniti directly.

[Q451990]

It would have been difficult to swap a 90-93 engine in to a 94 due to the different electrical connectors. In 2000 used engines for both series were readily available, so I can't imagine they would have taken the time to retrofit a 90-93 into that car. I think you can safely assume that you have a 94+ engine. The easiest telltale sign is the rocker cover (valve cover) design. 94+ is held down with acorn nuts, and uses an actual rubber gasket. 90-93 used small bolts, and the gaskets were made of liquid gasket. If you'd like to post a picture, that would give us a little more to go on - but I best you're safe.

[PaulR]

It would have been difficult to swap a 90-93 engine in to a 94 due to the different electrical connectors. In 2000 used engines for both series were readily available, so I can't imagine they would have taken the time to retrofit a 90-93 into that car. I think you can safely assume that you have a 94+ engine. The easiest telltale sign is the rocker cover (valve cover) design. 94+ is held down with acorn nuts, and uses an actual rubber gasket. 90-93 used small bolts, and the gaskets were made of liquid gasket. If you'd like to post a picture, that would give us a little more to go on - but I best you're safe.

Thanks for the help.

I didn't know that there were electrical connector differences between the two engines, so that knowledge, and the fact that mine does have the acorn nuts, gives me confidence that the chain tensioners should be reliable. BTW, the six digit number that I found on the block ends with "96", possibly indicating a 96 engine? But, the 96 engines did not have Variable Valve Timing. So, as with the 93 engine, will a 96 not be a direct replacement? Thanks.

Do you also know of any reports of engine vibrations with these engines? Mine has a vibration at 1500rpm. It is not caused by any of the accessories, and it is there in neutral and all gears. The vibration is not severe, but is enough to be noticeable. The only thing that I can think of that has enough mass to cause a vibration is the torque converter. Any thoughts?

The car has always had the vibration since I've owned it.

[Ryantzer]

The vibration you're feeling is most likely a misfire, which is probably due to a bad fuel injector (common failure point on the Q45). You can test all the injectors at the main injector harness connector above the back of the right valve cover.

[PaulR]

The vibration you're feeling is most likely a misfire, which is probably due to a bad fuel injector (common failure point on the Q45). You can test all the injectors at the main injector harness connector above the back of the right valve cover.

Thank you. I suspected an injector, but thought it more likely to be a mechanical imbalance. But, it does make sense to check the injectors.

[Ryantzer]

There aren't too many things that can cause a mechanical imbalance on most modern engines, a separated harmonic balancer being the most likely cause if it happens. Generally if something comes apart to the point that it would cause an engine imbalance, the imbalance is a minor consideration compared to whatever damage has caused it.

[PaulR]

There aren't too many things that can cause a mechanical imbalance on most modern engines, a separated harmonic balancer being the most likely cause if it happens. Generally if something comes apart to the point that it would cause an engine imbalance, the imbalance is a minor consideration compared to whatever damage has caused it.

The torque converter has enough mass that even a slight imbalance can have a noticeable effect.

[AZhitman]

Right, but that's not going to be the case here.

Ryan knows the VH45 inside and out. I'll bet if you inspect the plugs, one will look different.

I'd put all the money on an injector or a coilpack.

[PaulR]

Right, but that's not going to be the case here.

Ryan knows the VH45 inside and out. I'll bet if you inspect the plugs, one will look different.

I'd put all the money on an injector or a coilpack.

That's good enough for me. I'll do as Ryan suggested. I have already replaced all of the plugs, but still worth checking to look at the electrodes.

[AZhitman]

Yep, we were playing with VH engines back in the late 90's.

[Ryantzer]

There are easier ways to check for a misfiring cylinder than pulling the plugs - using a non-contact thermometer to measure the temps of the exhaust primaries works well, a cylinder with a lower temperature than the others is your misfiring cylinder. Personally I would check for a bad injector by testing the resistance of each one at the injector harness connectors - Infiniti was replacing injectors regularly on Q45s back when they were still under warranty, and they haven't improved with age.