I posted awhile back about '90 Q with overheating problem. Ive finally got the filler neck & cap replaced. Started the car & found the leak to be coming from the water pump.
Fred, you advised that I get a compression test which I'm planning to do. However, now that I know the water pump is leaking do I limp to the dealer & get the testing done? I'd hate to replace the water pump & then discover the engine is gone. Also, if there is a compression problem, where do I go from there?
Whet's the next step?
Oh, I remember now.
You had the Q with several bad overheats.(Or your wife did, by driving it while over heating w/ super low coolant)
You dont need to go to the dealer to have compression checked.A good independent you trust can check the engine as wella dn a compression check is just one part of that.Tell them you know of more than one severe overheat and to check this aluminum engine to see if its still good.
It would be best to tow, but certainly a few blocks are possible with no overheating, even if the waterpump is totally out.
(Beware bad stories exist from PPL trying to save on the tow and destroying a perfectly good engine that way, when their waterpump was toast, one of T3's customers had an overheat and then turned around driving the overheating engine back over a couple dozen miles completely destroying the engine).
If it was my own car, I would either tow (remember NEVER with the rear wheels on the ground) or drive less than a couple of miles.
Bring it to a shop you trust and then let them tell u if engine is gone or not. if it is, buy a known good used engine.(If therer are no independents around you really trust, use the dealer)If it is ok, everything checks out good, you will probably have to replace knock sensors which crack under overheats, as well as the pump.
Fred...
PS: How are things going with the wife?
You had the Q with several bad overheats.(Or your wife did, by driving it while over heating w/ super low coolant)
You dont need to go to the dealer to have compression checked.A good independent you trust can check the engine as wella dn a compression check is just one part of that.Tell them you know of more than one severe overheat and to check this aluminum engine to see if its still good.
It would be best to tow, but certainly a few blocks are possible with no overheating, even if the waterpump is totally out.
(Beware bad stories exist from PPL trying to save on the tow and destroying a perfectly good engine that way, when their waterpump was toast, one of T3's customers had an overheat and then turned around driving the overheating engine back over a couple dozen miles completely destroying the engine).
If it was my own car, I would either tow (remember NEVER with the rear wheels on the ground) or drive less than a couple of miles.
Bring it to a shop you trust and then let them tell u if engine is gone or not. if it is, buy a known good used engine.(If therer are no independents around you really trust, use the dealer)If it is ok, everything checks out good, you will probably have to replace knock sensors which crack under overheats, as well as the pump.
Fred...
PS: How are things going with the wife?
That's my problem. I don't know any independents within reasonable distance. But you did answer my question. I can get the test done before putting any money into it. Now to get it to the dealer is the next issue. I'd have to rent a flatbed. What's involved in the compression test? I was at the local autozone the other day & saw a compression test kit that included a gauge, hoses, & various fittings for different types of cars I'm assuming. Is this type of instrument a mechanic would use or do they use the engine's computer to obtain readings? I also saw a error code scanner OBD II by I believe the name was Accutron for $150. Anyone have any experience with these?
Things are OK with the wife. I get the car regardless which is why I'm trying to "refurbish" it.
Things are OK with the wife. I get the car regardless which is why I'm trying to "refurbish" it.
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Q451990
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- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
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Just remember your 90Q is not OBDII compatible. OBDII started in 1996, at least for the Q. If you're at all DIY inclined, a new water pump is fairly easy to install. You might try that and see how the engine runs with a water tight cooling system. The part will cost $93.75 from Scottsdale.
The compression isn't done with a computer. You have to pull the plugs, test dry, then test wet (squirt oil in cylinder) to compare readings. Large variances between cylinders will indicate a problem. Also if the compression goes up on the wet test you can narrow it down to rings - no change and it's valves.
Heath
The compression isn't done with a computer. You have to pull the plugs, test dry, then test wet (squirt oil in cylinder) to compare readings. Large variances between cylinders will indicate a problem. Also if the compression goes up on the wet test you can narrow it down to rings - no change and it's valves.
Heath
And the info continues to flow!
Thanks Heath!
I would consider myself moderately mechanically inclined. My grandfather has a garage where I could work on the car. That'll have to wait now that I'm replacing knock sensors on my '97. I'm still gonna get the compression test done before I start replacing anything. The local Nissan dealer charges $80. No DIY on the compression test. seems pretty involved.
I would consider myself moderately mechanically inclined. My grandfather has a garage where I could work on the car. That'll have to wait now that I'm replacing knock sensors on my '97. I'm still gonna get the compression test done before I start replacing anything. The local Nissan dealer charges $80. No DIY on the compression test. seems pretty involved.
I think the compression test Fred's talking about is for the cooling system. It's a very simple test and shouldn't cost much. Any shop with the right tool should be able to do it. They put an adapter on the radiator and pump up the system with air pressure until it hits operating pressure. Then they just let it sit for a while and check the pressure gauge after a certain time interval to ensure that the pressure hasn't dropped at all. A radiator/cooling shop would definitely be able to do the test, but of course you have to be wary of the dishonest ones. This one's really easy to cheat on.
I'm familiar with that test. But I believe Fred is refering to the cylinder pressure according to a previous thread.
"An engine that is overheated long enough to show running vibration from that should get a compression check as a minimum before you decide to put any money into fixing it."
Feel free to chime in if your "listening" Fred.
"An engine that is overheated long enough to show running vibration from that should get a compression check as a minimum before you decide to put any money into fixing it."
Feel free to chime in if your "listening" Fred.
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Q451990
- Moderator
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- Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
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If they'll do the compression test for $80 that's a bargain! I suspect when they figure out how hard it is to get to the plugs vs. the average Nissan they'll change their mind. Take in new plugs for them to install in the process - that's dirt cheap!
Keep in mind that you're probably going to have to replace the detonation sensors and harness on your 90 (and every hose under the plenum) since they've been baked. The sensors tend to crack with only one moderate overheat, so several bad ones and they're certainly toast. You might go ahead and replace the detonation sensor/ecu temp harness on your 97 while you're in there... they are the same design as the ones that give intermittant problems on the 90-96.
Heath
Keep in mind that you're probably going to have to replace the detonation sensors and harness on your 90 (and every hose under the plenum) since they've been baked. The sensors tend to crack with only one moderate overheat, so several bad ones and they're certainly toast. You might go ahead and replace the detonation sensor/ecu temp harness on your 97 while you're in there... they are the same design as the ones that give intermittant problems on the 90-96.
Heath
A lot of guys are..I dont think we ever had a 97t at a meet yet....Sorry, I associated the overheating with the cooling system test.
Yeah, no kidding! It's a 2-hour job MINIMUM just to do the plugs, and it takes me about 3-4 hours. I just did a compression test on my car on Friday. I have low compression on #6, so I'm pretty bummed. It is the rings. That's the same cylinder I had a pinched injector seal, so I guess it wore on it quite a bit at the time. I wouldn't hesitate to pull a head if I had to for my car, but a bad ring is well beyond my abilities. Guess I'll be keeping my eye out for a used G35 coupe. Black on black with all options!
Q451990 wrote:If they'll do the compression test for $80 that's a bargain! I suspect when they figure out how hard it is to get to the plugs vs. the average Nissan they'll change their mind. Take in new plugs for them to install in the process - that's dirt cheap!
Yeah, no kidding! It's a 2-hour job MINIMUM just to do the plugs, and it takes me about 3-4 hours. I just did a compression test on my car on Friday. I have low compression on #6, so I'm pretty bummed. It is the rings. That's the same cylinder I had a pinched injector seal, so I guess it wore on it quite a bit at the time. I wouldn't hesitate to pull a head if I had to for my car, but a bad ring is well beyond my abilities. Guess I'll be keeping my eye out for a used G35 coupe. Black on black with all options!
That's what I need to know! If the results of the compression test are not in my favor. Should I consider the engine gone?
Quote ». Guess I'll be keeping my eye out for a used G35 coupe. Black on black with all options! [/quote]Don't make me drool! My company has a partnership with Nissan/Infiniti where we can get cars @ 2.5% above cost. I've been ignoring the billboards & mags to keep my hormones in check!
Quote ». Guess I'll be keeping my eye out for a used G35 coupe. Black on black with all options! [/quote]Don't make me drool! My company has a partnership with Nissan/Infiniti where we can get cars @ 2.5% above cost. I've been ignoring the billboards & mags to keep my hormones in check!
Not necessarily gone. Moreso to justify looking at other cars. My car runs smooth; I had no idea anything was wrong. I only did the test cause I was doing the plugs anyway. It's just a little chink in the armor...something to think about before I replace the transmission if it were to ever fail on me.