VH45DE Bearing and Rod issues

[datsunmotorsports]

I was reading and still am reading through the search function results. I have run across a lot of VH45 engines with major mechanical failures in the bottom end. I believe I made a post about this at some point in the past, but it was within another thread I had started about something else.

I sold my G50 to a friend of mine. He started paying me then got into some trouble. He has agreed to give me the car back. I dont have a need for the car anymore. It has a VH45, trans, ECU, and harness from an 80K mile 96 G50. Im wanting to pull it out and put it in my project car. That would be a 1974 260Z. I'd like to make sure that I can abuse the VH45 as much as i want if Im going to go through the effort of building a custom sub frame for the front to cradle the engine far enough back that it fits.

My worry is that Im running across posts where the VH45 rods and bearings simply fail from normal abuse. And when i went out to look at Q's to buy one I ran across at least 10 cars with around 100K original miles on them with a rod knock of some sort. Some cars had more or less mileage. They were all obviously driven into the ground. All the Pick n Pull cars I ran across also suffered bottom end failures. The engine I own now was driven by an older gentleman and was taken care very well. All the same... it will have a rough life in my car. I don't wanna toss a rod.

Is there a preventative measure that can be taken to strengthen the bottom end up? Im seeing VH45 engines with Turbo chargers. These engines must being seeing stresses far greater than I could ever do with a relatively mechanically stock VH45. Is it simply a matter of replacing the OE bearings supplied by Nissan and using an after market fix or replacing the rods or possibly the rod bolts? Or is it in fact an inevitability that the bottom end was poorly designed and will fail in stock conditions if you run the piss out of it? Or is it just that Ive run across a lot of pre-94 Q's with other issues related to early G50 inherit problems and poor maintenance and a well maintained 96 Q drive train will be just fine getting all the abuse I can put it through?

What is your opinion?

[Q45tech]

Yes, incompentent owners can destroy a 90-96Q engine. It is simple just don't change the oil every 90 days or 3,750 miles.

My 90 Q [owned since Jan 90] now has 318,000 miles and the only internal work was replacing chain guides at 101,000 miles back in 1997.

I have been religious about oil and filters over 75 times for the first 100k valvoline 10w30, the next 150k was Mobil 1 10w30, now I'm back to Valvoline 10w40 except I use Mobil 1 0w40 during Dec-March.

You can NEVER CORRECT FOR A MISSED OIL CHANGE.

We have seen/purchased sludged up destroyed 94, 95, and 96 which were worthless at 100-130k from annual oil changes.

By the way my Q has used a modded ecu since 1994 with a 7300 rpm limit instead of oem 6900.

Hot new oil pressure still meets oem minimums even with Mobil 1 or it did last summer when last tested.

Hot Fresh Mobil 1 and oem filter at idle after a few hours at 90+F will tell you everything you need to know.

[qship96]

I bet you would have exact same results changing your oil every six months or 5000-7000 {whichever comes first} miles using Mobil 1 instead of at 3,750 miles/90 days

[SynisterQ]

I found this 450Z on youtube, pretty wicked. I'm assuming its a VH45DE. http://youtube.com/watch?v=GzKrmU0j1NU

[elwesso]

On all properly maintained VH45 the bottom end is fine.. Anyone can destroy it with enough help though.

The VH has one of the strongest bottom ends of any motor...

[datsunmotorsports]

Since this site changed its layout I've been finding other things around here. Some of it is harder and some of it is plain as day to find. I'm hoping you guys are right and most of the evidence points that direction to be completely honest. Must be the fact that the VH45 is a intricate machine. The Tolerances are tighter than engines of the 70's that I'm use to. Oil or temperature problems can easily lead to major engine failure. I just want to be sure that, that is in fact what is going on in most cases. Otherwise I can take the time to make preventative measures before I enter into such an undertaking.

BTW I have ran across 2 S30(first gen Z) cars that have VH45DE engines. The one above is featured at car domainhttp://www.cardomain.com/ride/563982

The other is featured at zparts.comhttp://www.zparts.com/showcase....html

These are the only 2 I know of for sure. I would think there are others, but are not so published.

Anyway thanks for the opinions hopefully a few more ppl will chime in and will help confirm one thing or another.

Thanks

[datsunmotorsports]

apparently, a lot of people on this site are confused about the using premium in their Q45 and what the difference is. If this is the case then its no wonder why I'm seeing these failures. I'm sure there is a good portion of Q owners out there that don't go on this site or others and know what the difference in fuel is and how bad anything less then premium is for their car so they buy 87.

So far I haven't even run across the correct reasoning why you should run premium fuel in your Q45. Just for future reference:The VH45 engine specifically has a 10.?:1 compression ratio. Because of the higher ratio and other variables such as combustion chamber shape and fuel management this engine needs a higher octane fuel. Most people kinda get part of that. IF you don't run premium in those conditions the lower octane fuel tends to start burning before it's suppose to causing something called "detonation" Instead of a clean burn the fuel mixture ignites in the combustion chamber just before its suppose to. This is a lot worse than it sounds. Detonation usually takes out the pistons and rod bearings. The forces are strong enough to shatter pistons. Over some amount of time it will cause rod knock.

took me a sec but I remembered an old site that is still uphttp://www.misterfixit.com/deton.htmall about detonation for ya.


Modified by datsunmotorsports at 10:00 AM 5/12/2008

[maxnix]

You're catching on very quickly.

One look at the crank beam and you will understand that few if any gasoline engines have a better bottom end. Can you say rigid?
Modified by maxnix at 11:32 AM 5/12/2008

[Q45tech]

Over the years we have replaced about 25 Q engines. After guide failure and the bent valves, sludge build up has been #2. In fact we have never seen a rod thru the block and many of these engines sound truely awful when running.

Usually those that have been oveheated are seized when finally shut off.

Not worth the time to dissassemble to find root cause of seize.

We have replaced, heads, pistons and BENT rods only because the sounds lead us to believe the engine might be saved after all except for vibrations 7and 1/2 cylinders run pretty well.

The combination of long oil changes and an oveheat may have been the final straw on some of them. Afterall the best synthetic cannot survive more than 90 seconds above a conventional when the oil goes to 350F.

[datsunmotorsports]

Over the years we have replaced about 25 Q engines. After guide failure and the bent valves, sludge build up has been #2. In fact we have never seen a rod thru the block and many of these engines sound truely awful when running.

Usually those that have been oveheated are seized when finally shut off.

Not worth the time to dissassemble to find root cause of seize.

We have replaced, heads, pistons and BENT rods only because the sounds lead us to believe the engine might be saved after all except for vibrations 7and 1/2 cylinders run pretty well.

The combination of long oil changes and an oveheat may have been the final straw on some of them. Afterall the best synthetic cannot survive more than 90 seconds above a conventional when the oil goes to 350F.

The engine that came out of my 92 was beaten up really bad. i put around 500 miles on it when I bought it. It had a tick it was low on power and the cooling system was on it's way out. I know the knock sensor was out and the ecu kept throwing that code and the injectors had some sort of problem as well. With all those issues I knew it was time to get a parts car. I had 1 short drive to make the car to where I could work on it and put the new engine in and 2 of the radiator hoses blew up. The engine basically overheated in 100 yards. I bought the new hoses as I would need them anyway and the tick got worse and I had a severe loss of power. The tick was now a knock and a tick... hehehe. After I got the engine out I pulled all the good parts off and found the problems. ALL the rubber under the intake manifold was in need of being replaced from heat soak and acids from petrol products. The tick was comming from the chain guides that never got replaced after 130K miles. The knock was coming from almost 1/4" of play in 2 of the rods. So I suppose that the injector knock sensor and overheating along with the PO which I know didnt take care of the car all added up to that mess. This the only VH45 Ive ever taken apart. So that is why I am asking.

I've seen the bottom ends on the VH BTW I love the crank cradle designs Nissan has been using. I like the rods too. I just didnt and dont know about the rod bolts and bearings, but we will find out. i have a good 80Kmile 96 VH45DE setup to figure out what to do with.

Also sounds like a good time to install a remote oil filer setup so the oil filter is in a better spot and an oil cooler if it goes into my 260Z...
Modified by datsunmotorsports at 11:58 AM 5/12/2008

[Q45tech]

The problem is that the early few years engines were hand assembled by real craftsmen and balanced AND TOLERANCED to perfection because they didn't know true durability. As the years progressed I believe they were less careful because they understood the engines better and why waste so much money when it wasn't necessary for typical US drivers who mistreated the engines [oil changes].

Why build a precison engine when the owner just destroys the precision with oil wear.

I've always wondered if the selection of the knock sensor [plastic housing which cracks at <300F] was not a way to ensure that under plenum hoses were changed at frequent intervals!

Something about the 1996 engine and sludge propensity has never been researched since so few made.............there are differences besides OBD2 and coils and lack of ignitors [integrated in coils/ecu].

Heck even the TCS engines behave differently due to add on extra TB and snout.

[Q45denver]

I would think the knock sensors would retard the timing before detonation got too bad? However, I understand some after market ECU's like JWT bypass the knock sensors. You may want to replace the rod bearings while you have the engine out, or at least check them for wear. I would think a preoiler would be a better option since most wear occurs at startup. You could also relocate the charcoal canister to facilitate removal of filter from the top.

I put 3 replacement engines in my 1990 Q. The original engine threw a rod through the block, another developed a bad rod knock and a third one had low oil pressure due to bad bearings. The dealer did not want to go to the trouble to disassemble any of them to find the root cause. I never had a problem with either of my 1995 Q's.

I had a 1972 240Z I drove for 6 years from new and beat the hell out of (teenager at time). Fine engine (never needed anything except tuneups) but I can only imagine what it would do with 300 HP. I understand it can make close to 300 HP if you do some head work and install Webers?
Modified by Q45denver at 10:56 PM 5/12/2008

[Q451990]

As the years progressed I believe they were less careful because they understood the engines better and why waste so much money when it wasn't necessary for typical US drivers who mistreated the engines [oil changes].

Why build a precison engine when the owner just destroys the precision with oil wear.

Do you think the JDM engines of the later years were different than the USDM engines, or did they just realize that the engines were being taken out of service in their own market at 60K and applied the same theory?

Heath

[Q45denver]

I think I heard that spun bearings might be due to use of front sump instead of rear sump and resulting damage when hard cornering. Can someone confirm?

[Q45tech]

What difference would a front or rear location make, when cornering is a left/right phenomena...................now in sustained acceleration above 0.5 g location is important BUT a Q cannot exceed 0.5G except between 30-40 mph in 1st gear.

Changing rear diff to 4.083 or supercharging or nitrous might require some thought about oil pan.

[tmorgan4]

Very interesting facts.....Seems like if a Q can reach 0.5G (Is that the point at which the oil pickup may get starved?) then these 240s and 300zxs with a VH45 (and 5 or 6 speed) would hit that point easier.

So far there are at least 2 document cases where someone spun bearings in multiple engines. Both had a front sump. I haven't heard of people having issues when converting to a rear sump like most do to fit the chassis anyway.

[elwesso]

i think the sump design has probably less to do with it (but certainly some) but more the capacity... 8 quart sump would be killer!!

[craigztoyz]

i think the sump design has probably less to do with it (but certainly some) but more the capacity... 8 quart sump would be killer!!

Also one of the front pans with an engine issue hit a curb or something, that allowed it to hit. Mine has the swaybar at the lowest height of the pan, so that is not an issue. I'm trying to keep it from sloshing around in the pan. Mazworx uses front sump in their S drag cars from what i was told, and have no problems. GTO's use a front sump too. If you have enough oil in capacity, and flowing down to overcompensate for the oil being drawn, no isssues. I have my pickup as far back as it can be and low at an angle(in case I should flatten pan, don't want it to starve).I am aiming for a lot more g's then that. Accusumps or similar are also a nice safety backup.