Stanis

iTrader: (2)

I'm dealing with a strange problem and I'm been hunting for answers on and off for months now. I have a 87 TII. The problem started about 500miles after my 1st rebuild (87k miles) One morning I noticed a buzzing noise that was consistent with rpms. It got louder over time. I used a mechanics stethoscope and pointed around and it was loudest under the front cover. When I built the motor the 1st time, I put a mazdatrix replacement thermopellet in and new rotor bearings.

I then disassembled the motor again with the help of a buddy and put it all back together changing the oil pump and pick up tube gasket. When it was open the 2nd time, I put an RB 85psi regulator and front shims in the motor. When I took the motor apart the 2nd time, we inspected all bearings and gears very carefully for wear. I wanted to make sure that there were no problems caused by the oil pump noise. The only wear spotted was in the oil pump rotor key-ways so we replaced the pump.

The noise only occurs when the motor is cold. It's absolutely horribly loud when the temps drop outside. When it was 45 the other night, I could hear the buzz distinctly from over 60ft away. Sounds like oil thinning out when it gets warm to me. If I grab the oil cooler feed hose I can feel the pulsing in the line and it's consistent with the buzzing noise. If I increase rpms, the buzzing goes faster. The return hose has no pulsing/vibrations to it. If I increase rpms over 2700ish, it moans like a squeaking whale. When the motor is cold, my aftermarket guage shows just about 95psi of pressure. When it's warmed up after a drive, it shows 55psi at idle and 85psi at cruise. I've tried using a lighter oil and that didn't help.

A troubleshooted step I tried was to remove the bypass thermostat from the oil cooler and put the cap back in. I started the car again this morning and the buzzing was still present so that ruled the thermostat out. Here is the t-stat from the cooler:


A few more of the t-stat and another t-stat here.

My only solution to this problem is to let the car warm up before I drive it. I've considered putting the e-shaft thermopellet back in to reduce oil pressure when cold. Maybe that will do it, but I shouldnt have the problem to start with. How do I find out if my oil pump is sucking air? Sump is full of oil. Perhaps the turbulent cooler feed hose is a result of air bubbles and they smooth out in the return hose. I've never heard of anyone having this problem before.

FC3Spitsfire

iTrader: (1)

i just wanted to note i have a very similar problem, but i havent had a rebuild. i have a 88 tII and when the weather gets cold, everytime i first start my car i get a loud buzzing from the engine bay. sounds almost like one of the warning buzzers but it comes from the engine. as the car warms up the noise goes away. also if the weather is warm it dosent happen at all.

langa

Hi,

I am having the same problem too. The noise is coming from the top oil cooler line which is vibrating and is quite loud.

@fossil_484, did you ever find the cause of the noise?

I have new oil cooler lines and I have replaced the foam surround that they go through as they pass between the radiator and the chassis, they are not vibrating against anything.

Langa.

T2 vert

iTrader: (5)

I had the same problem after I had installed duel oil coolers. After some research I found out that the oil lines were installed backwards, the inlet hose was installed on the outlet port. After switching the hoses the noise went away.

langa

I have the stock cooler and it is connected correctly.

Does this mean that it is likely a problem with the cooler rather than the block/oil system.

I think this noise only started after I replaced my cracked/leaking cooler with another second-hand one. Could it be a flow restriction in the cooler itself? The thermostat should be bypassing the core when the oil is cold and from the original post it would seem that it is not the thermostat as he tried another or none at all.

T2 vert

iTrader: (5)

Two of the three posters, four counting me, that had this problem had disconnected their oil line hoses. Connecting the hoses the right way solved my noise problem. I would double check the way your hoses are connected. For the stock cooler the short hose will go to the top port on the oil cooler the one opposite the thermostat. This hose is from the front cover of the engine. And if your hoses are correct, the only other thing I can think of would be the oil cooler or thermostat.

langa

Thanks for the info.

My cooler is definately connected correctly. I'll try and get hold of another thermostat and give that a try.

Stanis

iTrader: (2)

No resolution yet. Just went to check hoses a minute ago and they are correct, feed from front cover going to top port on cooler. How many of you guys have the stock oil bypass thermostat behind the front bolt and how many with the solid aftermarket ones? I am thinking about putting the stock one back in to see how it behaves.

I did run without the thermostat in the oil cooler and there was no change. This ruled out an oil cooler blockage.

RXnos1200

iTrader: (24)

55 psi at idle seems high. I have a RB oil regulator and also have the front cover shimmed.....When I first start the car in the morning the oil pressure gets up to 80 psi +.

After it warms up it starts to drop and at idle my pressure sits at 20 - 25 psi at 900 rpms.

Possible restriction in the oil lines or cooler? have u tried a different set of lines or another cooler? Good luck. Seems like you've had this situation going on for awhile....

langa

Have the cooler lines off at the moment as my car is off the road while I get my turbo re-built. Thermostat is ok and was installed correctly. Found that the top cooler hose was bent at quite a sharp angle when it comes off the banjo bolt to go around the radiator. The hose has chafed on a bracket and the outer cover is torn exposing the braid. Going to have to get it fixed, not worth the risk of a blown hose!!. Will try to route the hose as close to the factory hoses as I can and try and keep the run from too sharp an angle and see what happens. I'm sure I still have the plastic hose guide that they should be going through. The workshop that replaced the hoses originally did not route them through it properly so I took it off and padded the hose with high density foam, big mistake it seems as it has cost me a hose oh well one learns.

langa

Ok, seems I have this problem solved.

It could be one of two things (or both).

First the top oil cooler line as described above. Have a new hose installed and it has a much larger bend radius as it passes between the radiator and the chassis.

Secondly, I found that the bottom vac line on the front of the throttle body that goes to the underside of the Purge Control Valve had popped off. Reconnected with correct ID hose.

I have been driving the car for over a week now and no oil line noise

My guess then, is that it was either a restriction in the oil line due to the kink or too much pressure in the sump due to the PCV not being operated (which could also explain why the o-ring on the oil level sender started to leak).