Honda Prelude Forum - PreludeDriver.com

Hey guys.I have a 91 prelude si with b21a engine.Recently my oil light started blinking.I checked oil level---its fine? Can it blink to indicate other problems?Also blew a small hose below distributor( theres 3 of them in a T config )I've replaced all three but the oil light started blinking after that?? It got very hot but I shut it off right away,was wondering if it could of tripped somekind of sensor?Any Ideas would be great.Thanks Jeffrey.

Pictures of the hose that blew would be very helpful. Can you post some?

Your oil pressure light indicates low oil pressure, so it can blink even if the oil is topped up. I'm concerned that you may have a lubrication problem due to some kind of breakage somewhere. Check to see if there is oil in your coolant or coolant in your oil. I'd be careful with your car until your find out what is wrong. Were you running the car really hard when this happened?

Car got hot about 10 mins after starting morning drive to work.I shut it off and towed it home.There is no oil in the coolant.I was not running car hard.I've since made appt at Hondamotion to have car checked out,a local shop with great refrences.The guy I bought the car from told me he replaced everything when he put in a used (30,000) engine.It had been running fine,but check eng light would come on sometimes.After the small hose blew under the distributor the check oil light started comming on and off?I'll let you know what the mech tells me.

This baffles me, to be honest.

It's unlikely that your oil pump would fail, so unless the oil is finding it's way out of the engine, or is just low, your oil pressure light should stay off. It's possible that the oil pressure sensor could be faulty.

I think that the cooling problem is a seperate issue. Is you water pump working properly? Is your thermostat functioning?

I got my car back from the shop.The check engine light was due to a faulty o2 sensor(short),that was fixed.The blinking oil light is due to a faulty oil pump.The mech I took it too told me the scale was 10 to 52,10 being the bottom of the scale and 50 being the highest.At idle the meter read 12 and at speed it read 35.The light usually comes on when I'm coming to a stop(hence low pressure at idle)then goes off once I get to speed.He said to change the oil pump is fairly expensive due to where its at(behind or under or near timing chain???)He said that since it shows 35 at highway speeds and I only use it to commute that I should just drive it and would be fine.What do you guys think?He's been in business for over 20 years and has been highly recommended.Thanks a bunch!!!Jeffrey

That's the first time I've heard of a Honda oil pump failing. Wow.

If you are able to get acceptable pressure, I would say it is okay to drive your car a bit. In the long run though, you really should plan on changing out the pump. It's not the easiest thing to change, but then again, it's not the hardest either. I'm pretty sure it could be done without pulling the engine, although you will have to remove the timing belt to do it. If your timing belt needs changing anyway, you could do both at the same time.

Be careful not to rev your engine too high. B21s and B20s are known to have a problem oiling the #3 main bearing at high rpms for some reason. With your oil pump already struggling, you don't want to risk starving a main bearing too much. Be careful, and you should be fine for a bit.

Your oil pump has a pressure release valve on one end that jettisons extra pressure back into the pan. I have a slight feeling that I read something a while ago indicating that this valve can fail and cause the oil pump to lose effectiveness. I can't remember exactly what I read, but it's perhaps something that we should investigate further. If only the valve needed to be changed, you'd only have to drop the oil pan, which is dead easy.

I've attached a picture of an oil pump from a B20A5 I took apart a while ago. You're is likely exactly the same. You can see the outlet valve I speak of on the bottom left side. In that tube there is a metal plate, fastened with a cotter pin (which you can see). This, as I understand it, acts as a pressure check valve.

little OT here but i have a question.

how do you shim up a prelude oil pump to get higher oil pressures ?

CADster wrote:little OT here but i have a question.

how do you shim up a prelude oil pump to get higher oil pressures ?

You know, I have wondered exactly that many times. There is a way to do this, but I haven't found out how to do it on a Prelude. If you do a quick google search, there is discussion about doing this on Nissan 240s. I suspect that it wouldn't be hard to do to a prelude with the right parts.

There's more to think about though. Oil pressure isn't dependent on the oil pressure relief valve alone. The condition of your engine internals also plays a huge role. If your engine bearings are loose then your oil pump may never even be using the relief valve as enough oil is escaping into the engine by way of oiling the bearings. Higher engine rpm would raise the pressure, but I've read a lot of things saying that Honda oil pumps cavitate a bunch at high rpm, so even then you may not be utilizing the relief valve much, if at all.

With this in mind, in the interest of raising oil pressure, the first step would be to tighten up the internals. The relief valve will be shimmed stock to the correct pressure, and unless you're running some external units that require oil pressure, such as a turbo, you probably don't need much more pressure than you're already getting.

Driving the oil pump is a burden on the engine, and this increases with the pressure. theoldone.com claims that it's better to just work on the oil pump to increase its efficiency rather than doing a bunch of other stuff. Reducing pumping loss will help the engine churn out some good oil pressure without losing a bunch of horsepower.

Great question.

our pumps are not like other honda pumps so a shimming wont work (like with other import pumps)
our pumps use a cotter pin. (you can see it in your pic).

and i am turbo.