Volvo Penta MD22 questions

[razamataz]

Hi All

have a few questions regarding my VP md22

1. RPM meter only shows 500 rpm, alternator had regulator replaced lately as it wasnt charging - but previous to that it also showed 500 rpm
how is it corrected to show 900-1000 like it should in idle?

2. should an alternator give out 15V?

3. hr meter in the rpm gauge work sometimes, more often not
what should i look at to fix it?

4. I am almost sure my MD22 is MD22a - how do i know how much hp it has? some say there were 2 models, one with 50 and one with 60hp.
i read it goes according to max rpm and i can reach 3000 (+500 that missing)

Raz

[razamataz]

C'mon guys
I am sure there are some Volvo experts here....

just added story:
the copper? pipe from the HE rubber boot to the elbow had the drain plug break on me few months ago when i took the HE off and replaced the rubber boots

anyhow, i replaced the bolt and retreaded the pipe - dumb dumb dumb, i used a stainless bolt and that almost sank my boat
bolt was eaten away in less that 100hr of engine use, jut the head was found in the bilge

took the pipe off again - it feels solid to be retreaded again with copper bolt? but looks a bit pinkish inside....
maybe just replace with flexible hose...any insight?

[razamataz]

Do i need an offering to the Volvo experts?

[wholybee]

The alternator needs to be matched to the tachometer to read the correct speed. Some tachometers have a dial or other adjustment on the back for different alternators, and some regulators also have an adjustment. I don't know what you have, but that is what you need to check. Worst case, you might need a different tachometer to work with your alternator.
The hour gauge is a common failure. Search the Internet and there are places that fix it, but more often is replacing it.
I'm not sure on the bolt, my MD22p doesn't have rubber boots on the HE. So I don't know what that looks like. But you should go with what was there to begin with. The HE is very expensive, and would probably be cheaper for a new engine if it gets ruined.
As for the power, I think that is determined by the application and/or if it has a turbo. Because more RPMS equals more HP, simply installing the engine in an application where it runs at a higher RPM means more HP. And, there was also a turbo version.

[SV Confianza]

Can you specify which alternator, which regulator, and which tachometer you have?

For the hour counter, I know some panels do not advance the hour counter unless it's getting signal from the alternator for the tach. I'm not sure if the Volvo panel is the case. But they could be related?

When the regulator was replaced, were the connections re-terminated at the alternator and regulator? or were the same connectors used?

[DougR]

If your engine has the rubber caps on each end of the heat exchanger it is somewhere in the early 90s vintage. In about ‘95 or 96 they changed the HE to a different style which had no rubber caps.

During your vintage there were two models: MD22A and MD22A-L. The MD22A was 59hp@4000RPM and the MD22A-L was 50hp@3000. If memory serves me, the 22A had an oil cooler and the 22L did not.

As you know, the tach was driven by a signal from the alternator, so it pays to be sure the tach drive lead is well connected with no corrosion, etc. Make sure the belt isn’t slipping and the pulleys are the original size.

The tach was a “universal” type tach and a code had to be put into the tach depending on the engine model.......different tach drive ratios, or number of gear teeth counted, etc. The correct code for your engine is code #7. However if no one messed around with the tach, that shouldn’t have changed.
There was also a “fine tune” feature in the tach that could adjust maybe 10% up or down, but I don’t think it can handle 500 rpm.....

The hour meter is an LCD display which can be changed out by anyone with a little tech skill. It’s a VDO tach, and the part# for the LCD is “A2C00065115”.
I have found them for around $15 US. You can find change instructions on the internet.... The display is connected to the tach body with a ribbon wire, and I have been told by others that sometimes it’s just a little corrosion in the connector that causes problems. A little contact cleaner and a rub with a pencil eraser has things working again..... here is what the display looks like.

[razamataz]

Thanks guys

found many Youtube video's regarding that pesky hr screen - so i will look into it
my engine does indeed have rubber boots for the HE plus an oil cooler (have original reciept of previous owner and it was installed in 1995)

alternator is original, and i connected the same wire as it was (only internal regulator was replaced) - so still need to figure out rpm reading