oil temp higher than before

Joined
28 May 2000
Messages
1,626
Location
Hong Kong
Oil temp Before:

On a hot and humid 30c day .....

Nomal cruising on highway: 88c
Stuck in traffic: 95c
Spirited driving with lotsa vtec engagment: 105-110c

oil temp sensor is mounted at the oem oil cooler.

Oil temp Now:

After doing the following mods...
1. sos cam
2. sos LMA
3. sos valve springs + retainers
4. na2 gasket on na1 engine
5. all new engine o rings + rubber seals
6. sos cam plugs
7. sos big bore throttle

On a cool 15c not so humid day .....

Nomal cruising on highway: 93-95c
Stuck in traffic: 100-103c
Spirited driving with lotsa vtec engagment: 105-115c

What could possibly be the cause for the oil temp increase? na2 gasket? sos cams?

Thnx in advance.

Cheers,
Henry.
 
Hi Henry,

Just redo the readings at 30c to get comparable result. Maybe your thermostat was not fully open. Don't you have the SOS chip?

Besides that: how does she feel now? HP/TQ? :)
 
I guess I have to wait till next spring to reproduce the 30c weather ;)

I don't have any dyno sheet to compare with but the car feels a bit stronger. Or maybe it's psychological since I spent so much on the cams.... hehe.

Henry.
 
When the engine produces more power it also produces more heat.

Perhaps the rise in oil temperature is just a reassuring measurable indication that your modifications produced the result you were after.
 
Hmmm..... interesting theory, I hope that's the case :smile:

Another problem I notice, is that I hear metal knocking sound when the engine first started in the morning. It's pretty loud, like metal tapping on metal inside. As the oil temp raises, the sound slowly fade away and finally gone when the car is fully warmed up. It was never there before the rebuilt. Come to think of it, it sounds like the sound of engine knocking.... :eek:

Henry.
 
More problems....

I'm getting a CEL#22 (Front valve timing oil pressure switch) whenever I WOT and hit 7k or 8k.

Without hesitation, I replaced the front oil pressure switch under the froont spool valve right away and it's still giving me the CEL#22 :confused:

The car drives fine, rev fine, power is normal, the CEL is really bugging me! :mad:

Any idea?

Anybody knows the min oil pressure requirement for vtec to enage? I am getting 570kpa when I'm on the throttle.

Thnx in advance.

Henry.
 
VTEC engagement does not depend on oil pressure--at least not for the ECU. The sensor is there as a feedback mechanism to confirm whether the spool valve is opening or not. The fact that you're getting the code indicates that the ECU is trying to engage VTEC, but isn't getting confirmation that it's happening. Could be a problem with your oil pressure, the spool valve (clogged filter?), or even the harness. Since you replaced the pressure switch my guess would be there's not enough oil flow for whatever reason; however, others have reported lowered oil pressure at higher RPMs. With the light coming on at 7,000 RPMs (not 6,000) I wonder if this may be the case. The manual expects the pressure switch to see at least 392kPa with VTEC engaged at 5,000 RPMs. You said you get 570, but is that all the way through redline? Look on 6-17 of the service manual to begin troubleshooting. You'll need a multimeter and an oil pressure gauge.
 
I got my max 570kpa oil pressure from the oem oil pressure sending unit location at the oem oil cooler.

I followed the testing procedure from the manual and I'm getting over 50psi in the rear banks (within specs) when rev to 5k but I'm only getting 1/2 of that in the front banks, so I guess that's why my oil pressure switch tripped the CEL.

I've tried switching the rear spool valve with the front spool valve and the same low pressure occurs in the front bank so I guess we can rule out the spool valve assembly. Now, the question is.... why is the front bank getting such low pressure when the rear bank is getting adequate pressure? What keeps the oil pressure high in the heads?

It must have something to do with my recent upper engine work, I hope it's something simple and I hope I don't have to open her up again.

Henry.
 
Last edited:
Some more data....

All these years, my max oil pressure has always been around 680kpa, until a track day last year, my max oil pressure has dropped to 630kpa.

I recently installed a oil cooler and the max oil pressure has dropped a bit further to 570kpa.

Is the spool valve the only device holding the oil pressure at the head?

Now, I totally understand the saying "if it ain't broke, don't fix it!" :frown:

Henry.
 
The spool valve is the only thing that opens and closes, but pressure depends on both the pump and losses. Oil pressure can drop a lot if you have a bad journal or bearing. The looser the clearances, the greater the pressure drop. However, I *think* if something were "bleeding" in the front, it would show up in the rest of the system, and you wouldn't see 50psi in the rear. It sounds like a blockage IMO, though from your list of mods I'm not sure which could have cause a pressure drop.
 
Daedalus said:
The spool valve is the only thing that opens and closes, but pressure depends on both the pump and losses. Oil pressure can drop a lot if you have a bad journal or bearing. The looser the clearances, the greater the pressure drop. However, I *think* if something were "bleeding" in the front, it would show up in the rest of the system, and you wouldn't see 50psi in the rear. It sounds like a blockage IMO, though from your list of mods I'm not sure which could have cause a pressure drop.

Bad jornal or bearing? Are you talking about the crankshaft?

Blockage? That sounds bad! What can cause blockage to the front bank only? Maybe a mose of cockcroach got stuck inside? :eek:

I wonder if a totally malfunction spool valve can cause all this lost of pressure?

Thnx for your help.

Henry.
 
Concluding from your posts:

-loud metal knocking when cold
-higher oil temp
-significant difference in oil pressure between front and rear bank
-CEL code

-> something is wrong with the internals, maybe a bad bearing, but very hard to say from a x-miles distance. Let your tech have a look into it. I don't want to fear you but I think it has to be reopened again.
Who did the install?
 
nsxhk said:
Bad jornal or bearing? Are you talking about the crankshaft?

Blockage? That sounds bad! What can cause blockage to the front bank only? Maybe a mose of cockcroach got stuck inside? :eek:

I wonder if a totally malfunction spool valve can cause all this lost of pressure?

Thnx for your help.

Henry.

The cams too have journals that sit in bearings, just like the crankshaft. The spool valve could cause this, yes, but if you swapped them and the problem persists in the same head, the valve is not the cause. When you took pressure measurements at the sensor, with each of the spool valves, you had the valve jumped with 12V and the RPMs at 5,000 or so?
I agree with goldNSX the symptoms are a concern, but be sure to exhaust all possible methods of troubleshooting before opening up the engine. It's easier to troubleshoot a running engine than the pieces of a dismantled one. Narrow the problem down as much as possible before cracking the lid.
 
goldNSX said:
Concluding from your posts:

-loud metal knocking when cold
-higher oil temp
-significant difference in oil pressure between front and rear bank
-CEL code

-> something is wrong with the internals, maybe a bad bearing, but very hard to say from a x-miles distance. Let your tech have a look into it. I don't want to fear you but I think it has to be reopened again.
Who did the install?

My tech did all the installation :frown:

He remove the front valve cover last night.... he removed the cam holders and he said all 'seemed' ok. After he put back everything and do the front bank oil pressure test again.... and guess what? It's worse! He's not getting any oil pressure reading at all! It was late so he called it a night.

Sigh....

Henry.
 
Daedalus said:
The cams too have journals that sit in bearings, just like the crankshaft. The spool valve could cause this, yes, but if you swapped them and the problem persists in the same head, the valve is not the cause. When you took pressure measurements at the sensor, with each of the spool valves, you had the valve jumped with 12V and the RPMs at 5,000 or so?
I agree with goldNSX the symptoms are a concern, but be sure to exhaust all possible methods of troubleshooting before opening up the engine. It's easier to troubleshoot a running engine than the pieces of a dismantled one. Narrow the problem down as much as possible before cracking the lid.

Yes, valve jumped with 12v and 5k rev like it said in the manual. I saw him test the spool valve with 12v and it was clicking, but he didn't check the spool valve with a ohm meter tho.

Well, there's nothing we can do now since it's the holidays, guess we'll continue on Tuesday.

I was planning to go to a all paid for track day in a couple weeks, but I guess the car won't be going anywhere :frown:

Henry.
 
I was thinking the heads had not come off to do the mods, but I just realized that the NA2 gasket means head gasket. Try to confirm whether the head is oil-starved and, if so, the extent of the starvation. I'm wondering if you could remove all cams and then crank the engine to get the oil pumping, or would that damage something? Study the oil routing on 5-11 and figure out which galleries were touched when the mods were installed. The head may need to come off again and each passage flushed. Did you use liquid sealants or thick grease anywhere? They can squeeze into accessible oil passages and block them if you're not careful. Good luck.
 
Daedalus said:
I was thinking the heads had not come off to do the mods, but I just realized that the NA2 gasket means head gasket. Try to confirm whether the head is oil-starved and, if so, the extent of the starvation. I'm wondering if you could remove all cams and then crank the engine to get the oil pumping, or would that damage something? Study the oil routing on 5-11 and figure out which galleries were touched when the mods were installed. The head may need to come off again and each passage flushed. Did you use liquid sealants or thick grease anywhere? They can squeeze into accessible oil passages and block them if you're not careful. Good luck.

Initially, I didn't want my tech to remove the head. I didn't even want to touch the head gasket at all but my tech doesn't know how to change the valve springs and retainers without removing the heads so he decided to drop the entire engine and do a upper engine rebuild while he's at it. This is the result :(

I don't know about the damage when cranking an open engine, but it would be extremely messy!

I think he used some head gasket sealant and some valve gasket sealant.

Henry.
 
Boy, I doesn't sound good. It really sounds like something happened when the head was reinstalled. Like the head gasket may have been installed upside down, too much sealant, possibly a bad head gasket etc.....It seems like there is an oil passage that has been blocked. Look for any metal discoloration on the cam bearing area or on the head itself showing heating from oil starvation. This doesn't sound easy or cheap. Sorry to hear it.
Brad
 
I'm pretty sure the NSX engine is an interference motor, ( valves-pistons will hit when out of sequence), so pulling the cams and cranking to check oil flow is a BAD idea. With a little studing of the oiling circuits, you may be able to rig up an external pre. source to feed oil to the bank in question, and observe the situation, but I have to agree with a previous poster about the signs: bad sounds when cold, etc. are the tell tale signs of oil starvation, and damage usually occurs RIGHT NOW, leaving the owner SOL. Hope this is not the case for you! Good luck!
 
Tomrev said:
I'm pretty sure the NSX engine is an interference motor, ( valves-pistons will hit when out of sequence), so pulling the cams and cranking to check oil flow is a BAD idea. With a little studing of the oiling circuits, you may be able to rig up an external pre. source to feed oil to the bank in question, and observe the situation, but I have to agree with a previous poster about the signs: bad sounds when cold, etc. are the tell tale signs of oil starvation, and damage usually occurs RIGHT NOW, leaving the owner SOL. Hope this is not the case for you! Good luck!
Yes, it is an interference motor. But if you pull the cams the valves will all be closed, so they won't hit the pistons. Also, it shouldn't be too messy since there won't be any moving parts in the head to sling the oil around. The risk I see is that without the cams in place, the oil pressure will be nil. The crank would be turning as if on contiuous cold start. Probably not a problem if you wanted to just pop the starter for a few seconds to see which ports have oil flow and which don't.
 
nsxhk said:
but my tech doesn't know how to change the valve springs and retainers without removing the heads

:eek::eek::eek:!!!

I agree with the argument above that you should test the RUNNING engine as long as you can. But as TomRev mentioned the damage is right now! I wouldn't drive her anymore and would take the engine apart, esp. the front head (gasket). Interesting that you don't get any oil pressure AFTER the tech's (or whatever he is) 'check'. There is something seriously wrong.

Another note but that has nothing to do with no oil-pressure at all. The timing-belt was taken off during cylinder head removal, right? Was it put on correctly, meaning with the correct timing? I've heard of a guy where this wasn't the case and VTEC-engagement was like and Integra. But I think you should have noticed that before.
But again, I think there is a major problem with the oil-starvation.
 
Back
Top