My wife drives our 94 Q45t as her main source of transport. On Thursday, July 3rd, she was on her way to work which is about a 15 minute drive from our home. About a block before she got to the office the Q tried to stall out, she gave it a little gas and said that she heard/felt a bumping sound from the rear of the car. She made it to a stop light (a distance of about 1/10th of a mile) and the Q called it quits. She got a shove across the street to the gas station and gave me a call.
When she told me she heard bumping from the trunk I assumed that the fuel pump had died. No big deal. When I got to the gas station and opened the hood there was coolant sprayed on the engine and up onto the hood. All belts were fine and everything appeared to be in visual order. I turned the key to see if the temp gauge was reading hot and it wasn’t (could have cooled down before I got there), the engine wasn’t even that hot to the touch. I started the car and there was a constant clanking sound coming from the front of the engine like a rocker arm had broken. I shut her down as not to cause any further damage.
Long story short…my mechanic has the right or driver’s side valve cover off right now. The back spark plug (what number is that?) is missing its electrode and the coil is badly burnt. He doesn’t know where the electrode is. He says he can still hear that clanking sound when he spins the engine and he wants to pull it out and take the face off. He thinks it may be a tensioner (the timing chain is tight by the way).
I am no gear head so if anyone has any idea what the problem maybe or if I need to be more descriptive let me know. The plugs were changed about 15 months ago by the dealer and the car has 79k on it. Oil/filter changes every 3 months with Valvoline Durablend 10w30. The last 2 oil changes have been with Mobil 1 synthetic 10w30. The engine is superclean from what I can see with the valve cover off.
Any help is appreciated and there goes the G35 Coupe fund!
Serious engine trouble on my 94 Q45.
lemme summarize the details to help think.
79K 94Q t
1. Stalled out while driving in stopped traffic2. Coolant on the engine3. Clanking sound from front of engine while running4. Ruinned spark plug & burnt coil.5. Nothing obvious from a pulled valve cover.
Honestly, I have a hard time putting it all together.If it weren't for the coolant leak, I'd guess your engine is shot.
I'd start by tracing down the coolant leak.Turning the engine slow and watching the cams on the drivers side to see if the tensioner is the problemthen I'd pulling the LH tensioner - this can be done fairly painlessly.
79K 94Q t
1. Stalled out while driving in stopped traffic2. Coolant on the engine3. Clanking sound from front of engine while running4. Ruinned spark plug & burnt coil.5. Nothing obvious from a pulled valve cover.
Honestly, I have a hard time putting it all together.If it weren't for the coolant leak, I'd guess your engine is shot.
I'd start by tracing down the coolant leak.Turning the engine slow and watching the cams on the drivers side to see if the tensioner is the problemthen I'd pulling the LH tensioner - this can be done fairly painlessly.
Tie-strap the chain to both cam sprockets before removing the tensioner *just in case*. I'll echo Forecast--VERY odd. I fear the worst--the electrode went through the head, allowing all the coolant to escape, and perhaps damaging something else to cause all the noise. Please verify for us what brand plugs were used. The fact that the coil is burnt suggests an ongoing problem. It's the #7 cylinder.
My first inclination was piston-valve interference as 911/Q45 suggests - however the accompaning burned coil convinced me otherwise. That sounds more like detonation destroyed the plug in the past and the coil's been shorting for some time now, maybe a month.
Of course a dead cylinder would have shown up as vibration at idle and slightly off power.
If the timing was off, turning the engine by hand would show it.
A blown head gasket would explain the coolant leak. Why else does the mechanic think this? The coolant leak can be traced by pressuring the system with a special hand pump.
Where is clanking sound exactly? Turning the engine by hand, it should be easy to pinpoint. There are only seven moving parts in the timing compartment (oil pump, two tensioners, two moving chaing guides and two VTCs). If the sound is anywhere else, it will mean getting a new engine.
Of course a dead cylinder would have shown up as vibration at idle and slightly off power.
If the timing was off, turning the engine by hand would show it.
A blown head gasket would explain the coolant leak. Why else does the mechanic think this? The coolant leak can be traced by pressuring the system with a special hand pump.
Where is clanking sound exactly? Turning the engine by hand, it should be easy to pinpoint. There are only seven moving parts in the timing compartment (oil pump, two tensioners, two moving chaing guides and two VTCs). If the sound is anywhere else, it will mean getting a new engine.
-
Q451990
- Moderator
- Posts: 11030
- Joined: Tue Jul 23, 2002 8:21 am
- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
- Location: Columbia, SC
- Contact:
If things don't work out with your engine I'd certainly buy the new longblock on eBay. It's cheap, and no one has come close to the $1400 asking price in the previous two auctions. I'd be really interested to know what happened though - very rare to hear of any Q engine with a major failure with low mileage!
I'd think that an overheat (broken plenum hose?) would have to exist for a while to have something really break... any history of other overheats?
Heath
I'd think that an overheat (broken plenum hose?) would have to exist for a while to have something really break... any history of other overheats?
Heath
UPDATE.
My tech called it quits because he realized he is not familiar enough with the Q engine. He told me it sounded like there were marbles in the front face around the timing chain area. There was very little water/coolant spillage when he removed the plenum and he said he was expecting a lot. I am considering having her shipped to T3 or towing it to a guy here in town that has done a few chain jobs on first gen Qs. I misspoke about the bad plug. It was number 4.
Any ideas on what could be making the “marble rolling” sound?
Any ideas on what could be making the “marble rolling” sound?
stumped but really curious now.
I haven't a clue. I've been all the way through a Q engine and I can't imagine easily what would make marble sounds. Bad tensioners will make a loud tapping sound. I don't think a Bad VTC will make anysound.
Something broken off and is surfing the chains? A bolt come loose from a cam sproket?
Please keep me updated
Unfortunately it doesn't bode well for your pocketbook since I'm guess it will call for an engine transplant to keep that car running.
Personally if you are planning to keep the Q on the road I'd look seriously at the cost of towing it to Atlanta. I've no direct experience with the shop, but the volume of Infiniti's they work on will become a discount on the time taken and a truer estimate of the actual cost.
Nothing is worse than getting a tech in over his head on fixed cost job.
Something broken off and is surfing the chains? A bolt come loose from a cam sproket?
Please keep me updated
Unfortunately it doesn't bode well for your pocketbook since I'm guess it will call for an engine transplant to keep that car running.
Personally if you are planning to keep the Q on the road I'd look seriously at the cost of towing it to Atlanta. I've no direct experience with the shop, but the volume of Infiniti's they work on will become a discount on the time taken and a truer estimate of the actual cost.
Nothing is worse than getting a tech in over his head on fixed cost job.
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Got an interesting call from a large dealer in Atlanta. During the winter they had rebuilt a 92 Q engine using more than $4500 worth of retail parts [and 55 hours of labor][to keep their Master tech earning when things were slow] [he worked for us for 5 years by the way].........because they could not find any suitable 90-93 engines to do swapouts.The Q owner backed out of the deal and junked the car for parts.
They have had the long block motor sitting for 4.5 months and offered it to us for $2500 their actual cost might have been $3,900-$4,300.
Even at $2500 it is still too expensive to use to keep within a $5500 price range -- very very few owners contemplate spending that much now on a 90-93 engine swap.
You gotta be careful about any engine replacement the only way is to change everything while the engine is out and easy to work on, otherwise you get nickeled and dimed to death in the years following the swap redoing all the old accessory parts/hose/sensors you neglected to change.
Shops can't warranty what they don't change and 99% of the time what they don't change turns out to be the future problem.
Many just low ball the swap and change nothing hoping they make 12,000 miles or less and tell the owner hey we didn't change that so it wasn't our fault ..........sure they charged $1,000 less but the engine [system] now needs another $1500 and will need another $1500 next year.
Don't always take the low bidder unless you know exactly what is occuring. An extra $500-$1,000 spent on the swap while the work is easy can save you $2,000 when it must be done again with the engine in the car.
They have had the long block motor sitting for 4.5 months and offered it to us for $2500 their actual cost might have been $3,900-$4,300.
Even at $2500 it is still too expensive to use to keep within a $5500 price range -- very very few owners contemplate spending that much now on a 90-93 engine swap.
You gotta be careful about any engine replacement the only way is to change everything while the engine is out and easy to work on, otherwise you get nickeled and dimed to death in the years following the swap redoing all the old accessory parts/hose/sensors you neglected to change.
Shops can't warranty what they don't change and 99% of the time what they don't change turns out to be the future problem.
Many just low ball the swap and change nothing hoping they make 12,000 miles or less and tell the owner hey we didn't change that so it wasn't our fault ..........sure they charged $1,000 less but the engine [system] now needs another $1500 and will need another $1500 next year.
Don't always take the low bidder unless you know exactly what is occuring. An extra $500-$1,000 spent on the swap while the work is easy can save you $2,000 when it must be done again with the engine in the car.
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
We will known next week as it is being dropped off [towed from Fla] this Saturday. This will only be the 4th [94-96] major failure we have seen.........2 overheats and one lack of oil changes so far]............well maybe another category we will have to see Freds. I have heard of 2 more but we will have to wait and see.
Almost time for some 97 Q to be failing got to check with dealers to find out what they are seeing.
Almost time for some 97 Q to be failing got to check with dealers to find out what they are seeing.
-
jefftrexler
- Posts: 174
- Joined: Thu Jul 25, 2002 9:15 pm
- Car: 1991 Nissan Maxima
eQlipse wrote:Here's a possiblity depending on how your situation turns out!
NEW HOPE
I'm planning on visiting that wrecking yard today ,since they are in the same town as I, just to see what they have available for 90-95 Q45's. I'll make a list of goodies and get back to you folks. Oh...and I'll scope out that Q engine as well.
-
Q45tech
- Moderator
- Posts: 14296
- Joined: Tue Apr 30, 2002 3:19 am
- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The preliminary diagnosis is the Autolight plugs started the whole scenario destroying #7 coil and plug. The #7 electrode has not been found. All the even bank plugs were fouled but the electrodes were there.It appears that all the misfiring [both banks] has done damage to the precats and maybe the cats themselves. The passenger side is blocked [melted] and no oxygen sensor readings on either side they maybe melted also.
The engine can be made to run at 1500 rpm but the cats start to heat up quickly. We will be spending tomorrow trying to narrow down the details.
It appear as this point that the internals are fine other than some cam wear [previous owners oil change habits].......the only question is the exhaust valves. But we'll have to wait for the passenger side leak down till the back pressure is down to normal...........passenger exhaust manifold precats, 2 new O2 sensors and possibly cats.
Members please use nothing but NGK plugs and oem sensors.
The engine can be made to run at 1500 rpm but the cats start to heat up quickly. We will be spending tomorrow trying to narrow down the details.
It appear as this point that the internals are fine other than some cam wear [previous owners oil change habits].......the only question is the exhaust valves. But we'll have to wait for the passenger side leak down till the back pressure is down to normal...........passenger exhaust manifold precats, 2 new O2 sensors and possibly cats.
Members please use nothing but NGK plugs and oem sensors.
-
s13sr20chris
- Posts: 4148
- Joined: Tue Jun 10, 2003 9:32 am
- Car: '89 Nissan S13 w/redtop running 13psi and not leaking fuel anymore
- Contact:
My error was making the assumption that sense the previous owner had the car dealer maintained that the plugs would be OEM. He had it done a month or so before I bought the car. Being ignorant to the Q, I didn't check to see about the plugs. Assuming that they were changed (and they were, otherwise they would be old OEM plugs) they should have about 15k on them. Pretty pitiful plug to say the least.
I'm confident that Dennis and the crew will get it ironed out. I'll have some peace of mind knowing exactly what has been done to my car as oppsoed to wondering if the previous owner did A, B and C. In the meantime the old Maxima is carrying my family hither and yond like a champ.
Please continue to post updates Dennis and thank you guys for your interest and help.
I'm confident that Dennis and the crew will get it ironed out. I'll have some peace of mind knowing exactly what has been done to my car as oppsoed to wondering if the previous owner did A, B and C. In the meantime the old Maxima is carrying my family hither and yond like a champ.
Please continue to post updates Dennis and thank you guys for your interest and help.