Hi all,

I've been getting all the stuff together to swap a new (used) motor into my '03.

I realize of course that salvage engines are a crapshoot and that being said ... I have my eye on a couple of local candidates. There is nothing with super low mileage (which is to be expected at this stage in the game I guess) sooo ...
If you had the choice between a higher mileage engine with excellent compression numbers vs a lower mileage engine with mediocre (acceptable) compression numbers, which way would you go?

My '99 ran like a swiss watch until the day I scrapped it (380 000 kms - body was rotten) so I know I high mile motor can run well.

My other thought is what if the engine with very good compression is actually a replacement that was installed at some point in the life of the car (maybe by the dealer) and is actually much lower mileage than the odometer on the car is reading?

Anyway ... opinions?

 

For there too be any loss in compression there would have to be a leak in the cylinder or worn out piston rings. Ontop of that overtime you will lose more compression. I would prefer a higher mileage motor with excelent compression personaly. For all you know a 40,000 mile motor could be 85% city mileage just as much as a higher mileage motor could just be highway miles.

 

Thanks for the input.

As we all know, our cars (quite a few of them anyway) have built in problems in this department (bad rings from the factory and pre-catalytic converters that self destruct and in turn score the fu#k out of the cylinder bores) so when I see the odd one with good compression it catches my eye. My car falls into category 2 ... the front pre-cat puked and the right bank burns oil pretty good. It's obvious when you pull the upper intake. The right bank lower intake is black and slimy with blow-by while the left bank is clean.

This is just one of a litany of issues which is why I am pulling this boat anchor out.

Most of the engines I've found have compression of 130-150. I have found one with 165 and one with 170! 185 is the number right off the assembly line so 170 seems pretty darn good @ 135 000 miles (for an '04 VQ).

Please chime in with your thoughts everyone.

 

At time of pull mine had 175 psi at 181k not-so-easy miles. 170 sounds like poor maintenance.

There really is little point to a straight swap. 5.7 swap is ideal and the motors are cheap. I saw one with 80k for like 600 bucks (2008 altima). If you can find them at a "u pull it" yard, then they're dirt cheap (235 with core charge here).

 

I agree! And I wish those prices were the same in my neck of the woods,but sadly they're prone to the supply and demand around here,where a high milage vq goes for $600+ and a low milage 09+ over $1500

 

Ideal I guess if you have the time and the facilities of which I have neither. Straight swap = Straight forward = less cash outlay and back on the road ASAP.